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All Textbook Solutions for Conceptual Physical Science Explorations
Consider molecules of hydrogen (tiny ones) and oxygen (bigger one ) in a gas mixture. If they have the same kinetic energy ( they will at same temperature ), which molecule have the greatest average speed?According to the work-energy theorem, in the absence of friction, if you do 100J of work on a cart while pushing it across a horizontal surface, how much will you increase its kinetic energy?When a driver applies brake to keep a car going downhill at constant speed and constant kinetic energy, the potential energy of the car decreases. Where does this energy go? Where does its most of it appear in a hybrid vehicle?On a slide a child has potential energy that decreases by 1000 J while his kinetic energy increases by 900 J . What other form of energy is involved, and how much?Consider the identical balls released from rest on tracks A and B as shown. When they reach at the right ends of the tracks, which will have the greater speed? ( Hint: Will their KEs be the same at the end?) Which will get to the end in the shortest time? (Considering the extra speed in the lower part of the track B, which ball has the greatest average speed on the ramps?)You tell your friend that no machine can possibly put out more energy than is put into it, and your friend states that a nuclear reactor puts out more energy than is put into it. What do you say?Two lumps of clay with equal and opposite momenta have a head-on collision and come to rest. Is momentum conserved? Is kinetic energy conserved? Why are your answers different?An automobile engine runs on compressed air. This means no pollution in the vicinity of the car. Does it also mean no energy is required? (Hint: Is energy required to compress air? )Consider the swinging-balls apparatus. If two balls are lifted and released, momentum is conserved as two balls pop out the other side with same speed as the released balls at impact. But momentum would also be conserved if one ball popped out at twice the speed. Can you explain why this never happens? (Hint: If the collision is perfectly elastic, what besides momentum would have to be conserved? Can you see why this exercise is here rather than in the previous chapter on the momentum? )Does a high-efficiency machine degrade a relatively high or relatively low percentage of energy to thermal energy?If an automobile had a 100% efficient engine, transferring all of the fuel's energy to work, would the engine be warm to your touch? Would its exhaust heat the surrounding air? Would it make any noise? Would it vibrate? Would any of its fuel go unused?A friend says that the energy of the oil and coal is actually a form of solar energy. Is your friend correct, or mistaken?How many joules of work are done when a force of 1N moves a book 2m?( a ) How much work is done when you push a crate horizontally with 100N across a 10m factory floor? ( b ) If the force of friction on the crate is a steady 70N , show that the KE gained by the crate is 300J . ( c ) Show that 700J is turned to heat.This question is typical on some drivers license exam: A car moving at 50km/h skids 15mwith locked brakes. How far will the car skid with locked brakes at 150km/h?A force of 50N is applied to the end of a lever, which is moved a certain distance. If the other end of the lever moves one-third as far, show that the force it exerts is 150N.Consider an ideal pulley system. If you pull one end of the rope 1m downward with a 50N force, show that you can lift a 200N load one-quarter of a meter high.How many watts of power expanded when a force of 1N moves a book in a time interval of 1s ?How much work is done on a 100-kg crate that is hoisted 2 m in a time of 4 s ? (a) 200 J (b) 500 J (c) 800 J (d) 2000 JHow much power is required to raise a 100-kg crate a vertical distance of 2m in a time of 4s ? (a)200W (b)500W (c)800W (d)2000WRaising an auto in a service station increases its potential energy. Raising it twice as high increases its potential energy by (a)half. (b)the same amount. (c)twice. (d)four times.A model airplane moves three times as fast as another identical model airplane. Compared to kinetic energy of the slower airplane, the kinetic energy of the faster airplane is (a) the same for level flight. (b) twice as much. (c) four times as much. (d) more than four times as much.Which of the following equations is most useful for solving a problem that asks for the distance a fast-moving box slides across a post office floor and comes to a stop? (a)F = ma (b) Ft=mv MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOraiaads hacqGH9aqpcqqHuoarcaWGTbGaamODaaaa@3C11@ (c) KE=1/2 m v 2 MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4saiaadw eacqGH9aqpdaWcgaqaaiaaigdaaeaacaaIYaaaaiaad2gacaWG2bWa aWbaaSqabeaacaaIYaaaaaaa@3CF7@ (d) Fd=1/ 2m v 2 MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOraiaads gacqGH9aqpcqqHuoardaWcgaqaaiaaigdaaeaacaaIYaGaamyBaiaa dAhadaahaaWcbeqaaiaaikdaaaaaaaaa@3E77@A shiny sports car at the top of a vertical cliff has potential energy of 100MJ relative to the ground below. Unfortunately, a mishap occurs and it falls over the edge. When it is halfway to the ground, its kinetic energy is (a) The same as its potential energy at that point. (b) negligible. (c) about 60MJ. (d) more than 60MJ.When a hybrid car brakes to a stop, much of its kinetic energy is transformed to (a) heat. (b) work. (c) electric potential energy. (d) gravitational potential energy.In an ideal pulley system, a woman lifts a 100-Ncrate by pulling a rope downward with a force of 25N. For every 1-meter length of rope she pulls downward, the crate rises (a) 50centimeters. (b) 45centimeters. (c) 25centimeters (d) none of these.When 100J are put into a device that puts out 40J, the efficiency of the device is (a) 40. (b) 50 (c) 60 (d) 140A machine cannot multiply (a) forces (b) distances. (c) energy (d) All of these.What connection did Newton make between a falling apple and the moon?What does it mean to say something moving in a curve has a tangential velocity?In what sense does the Moon "fall?"State Newton's law of universal gravitation in words. Then state it again in one equation.How does the force of gravity between two bodies change when the distance between them is doubled?How does the thickness of paint sprayed on a surface change when the sprayer is held twice as far away?7RQWhat is the magnitude of gravitational force between two 1-kilogram bodies that are 1meter apart?What is the magnitude of the gravitational force between the Earth and a 1-kilogram body?What do we call the gravitational force between the Earth and your body?When G was first measured, the experiment was called the weighing the Earth experiment. Why?With no gravity, a horizontally moving projectile follows a straight-line path. With gravity, how far below the straight-line path does it fall compared with the distance of free fall?A ball is batted upward at an angle. What happens to the vertical component of its velocity as it rises? As it falls?With no air drag, what happens to the horizontal component of velocity for the batted baseball?How can a projectile "fall around the Earth?"Are the planets of the solar system simply projectiles falling around and around the sun?Why does the speed of a satellite undergo change in an elliptical orbit?At what part of an elliptical orbit does a satellite have the greatest speed? The least speed?What is the minimum speed for orbiting the Earth in the close orbit? The maximum speed? What happens above this speed?What makes the Earth round?The planet and its much less massive moon gravitationally attract each other. Compare the gravitational attraction between them from greatest to least.Three boys on three towers of the same height toss a ball at the velocities shown. Compare the horizontal distances from the tower that the balls travel when hitting the ground, from greatest range to least.Comment on whether or not this label on a consumer product should be cause for concern. CAUTION: The mass of this product pulls on every other mass in the universe, with an attracting force that is proportional to the product of the masses and inversely proportional to the square of the distance between them.Gravitational force acts on all bodies in proportion to their masses. Why, then doesnt a heavy body fall faster than a light body?What would be the path of the moon if somehow all gravitational forces on it vanished to zeroIs the force of gravity stronger on a piece of iron than on a piece of wood if both have the same mass Defend your answer.Is the force of gravity stronger on a piece of paper when it is crumpled Defend your answer.What is the magnitude and direction of the gravitational force that acts on a teacher who weighs 1000N at the surface of the earthThe Earth and the Moon are attracted to each other by gravitational force. Does the more massive Earth attract the less massive Moon with a force that is greater, smaller, or the same as the force with which the Moon attracts the Earth?What do you say to a friend who says that if gravity follows the inversesquare law, when you are on the 20th floor of a building gravity on you should be onefourth as much as when you're on the 10th floorA friend says that astronauts in orbit are weightless because they are beyond the pull of Earths gravity. Correct your friends ignorance.Is the horizontal component of the velocity for a projectile affected by the vertical component Defend your answer.A heavy crate accidentally falls from a highflying airplane just as it flies directly above a shiny red sports car parked in a car lot. Relative to the car, where will the crate crashAt what point in its trajectory does a batted baseball have its minimum speed? If air drag can be neglected, how does this compare with the horizontal component of its velocity at the other points?A park ranger shoots a monkey hanging from a branch of a tree with a tranquilizing dart. The ranger aims directly at the monkey, not realizing that the dart will follow a parabolic path and thus fall below the monkey. The monkey however sees the dart leave the gun and lets go of the branch to avoid being hit. Will the monkey be hit anyway? Defend your answer.Since Earth is gravitationally attracted to the Sun, why dont we simply crash into the Sun?15TE16TEIf a cannonball is fired from a tall mountain, gravity changes its speed all along its trajectory. But if it is fired fast enough to go into circular orbit, gravity does not change its speed at all, why?When an Earth satellite is placed into a higher orbit, what happens to its time for making a complete orbit? In other words, what happens to its period?If a space vehicle circled Earth at a distance equal to the Earth-Moon distance, how long would it take to make a complete orbit?Some people dismiss the validity of scientific theories by saying they are only theories. The law of universal gravitation is a theory. Does this mean that the scientists still doubt its validity? Explain.If you stood atop a ladder that was so tall you were three times as far from the Earths center as you were standing on the Earths surface, how would your weight compare with its present valueFind the change in the force of gravity between two planets when the masses of both the planets are doubled but the distance between them stays the same.Find the change in the force of gravity between two planets when their masses remain the same but the distance between them is increased by ten times.Find the change in the force of gravity between two planets when the distance between them is decreased by ten times.Find the change in the force of gravity between two planets when the mass of the planets dont change but the distance between them is decreased by five times.Find the change in the force of gravity between two objects when both masses are doubled and the distance between them is also doubled.Consider a bright point of light located 1 m from a square opening of area 1 square meter. Light passing through the opening illuminates an area of 4 m2on a wall 2 m from the opening. (a) Find the area illuminated if the wall is moved to a distance of 3 m, 5 m or 10 m. (b) How can the same amount of light illuminate more area as the wall is moved farther away?Calculate the force of gravity between the Earth (61024kg) and the Sun (21030kg) . The average distance between the two is 1.51011m.A 3-kg newborn baby at the Earths surface is gravitationally attracted to Earth with a force of about 30N . (a) Calculate the force of gravity with which the baby on Earth is attracted to the planet Mars when Mars is closest to Earth. (The mass of Mars is 6.41023kg and its closest distance is 5.61010m .) (b) Calculate the force of gravity between the baby and the physician who delivers it. Assume the physician has a mass of 100kg and is 0.5m from the baby. (c) How do the forces compareStudents in a lab measure the speed of a steel ball launched horizontally from a tabletop to be 4.0m/s If it takes 0.5s for a ball to fall from the table to the floor below, where should they place a small piece of paper so that the ball will hit it when it landsThe force of gravity between two planets depends on their (a) masses and distance apart. (b) planetary atmospheres. (c) rotational motions. (d)All of these.When the distance between two stars is reduced by 1/2 , the force between them (a) decreases by 1/2. (b) decreases by 1/4. (c) increases by twice times as much. (d) increases four times as much.If the Sun were twice as massive, its pull on Mars would be (a) unchanged. (b) twice. (c) half. (d) four times as much.When an astronaut in orbit is weightless, he or she is (a) beyond the pull of Earth's gravity. (b) still in the grip of Earth's gravity. (c) in the grip of interstellar gravity. (d) None of these.When no air resistance acts on a fast-moving baseball, its acceleration is (a) downward, g. (b) due to a combination of constant horizontal motion and accelerated downward motion. (c) opposite to the force of gravity. (d) zero.6RATIn circular orbit, the gravitational force on a satellite is (a) constant in magnitude. (b) at right angles to satellite motion. (c) Both of these. (d) Neither of these.8RATA satellite in elliptical orbit Earth travels fastest when it moves (a) closest to Earth. (b) far from Earth. (c) in either direction-the same everywhere. (d) between the near and far points from Earth.A satellite in Earth orbit is above Earth's (a) atmosphere. (b) gravitational field. (c) Both of these. (d) Neither of these.Distinguish between mass density and weight density. What are the mass density and weight density of water?How does the pressure exerted by a liquid change with depth in the liquid? How does the pressure exerted by a liquid change as the density of the liquid changes?How does water pressure 1meter below the surface of a small pond compare to water pressure 1meter below the surface of a huge lake?If you punch a hole in the side of container filled with water, in what direction does the water initially flow outward from the container?Why does buoyant force act upward on an object submerged in water?How does the volume of a fully submerged object compare with the volume of water displaced?How does the buoyant force on a fully submerged object compare with the weight of water displaced?What is the mass in kilograms of 1L of water? What is its weight in newtons?If a 1-L container is immersed halfway in water, what is the volume of water displaced? What is the buoyant force on the container?Does the buoyant force on a floating object depend on the weight of the object or on the weight of the fluid displaced by the object? Or are these two weights the same for the special case of floating? Defend your answer.What weight of water is displaced by a 100-ton floating ship? What is the buoyant force that acts on this ship?By how much does the density of air increase when it is compressed to half its volume? Its pressure?How does the downward pressure of the 76-cm column of mercury in a barometer compare with the air pressure at the surface of the dish of mercury that it stands in?How does the weight of mercury in a barometer tube compare with the weight of an equal cross section of air from sea level to the top of the atmosphere?Consider two tubes of equal cross-sectional area. One is a 76-cm-tall tube of mercury and the other a 10.3-cm-tall tube of water. Which weighs more? Which exerts more pressure at the bottom of the tube?What happens to the pressure in all parts of a confined fluid when the pressure in one part is increased?Does Pascal's principle provide a way to get more energy from a machine than is put into it? Defend your energy.A balloon that weighs 1N is suspended in the air, drifting neither up nor down. How does the buoyant force acting on it compare with its weight? What happens if the buoyant force decreases? Increases?19RQWhat do peaked roofs, convertible tops, and air-plane wings have in common when air moves factor across their top surfaces?Calculate the density of a block of mass 22kg that has a volume of 2.6cm3.Calculate the density of 3L of a liquid that has a mass of 2.6kg.Calculate the density of a gas with a mass of 4.3kg and a volume of 3.0m3.Calculate the pressure in N/m2 at the bottom of the Hoover dam. The depth of water behind the dam is 220m. (Neglect the pressure due to atmosphere.)Calculate the water pressure at the base of a 30m-tall water tower.The three metal balls are held suspended and submerged in water. Rank the buoyant force on each from greatest to least.A buoyant force acts on each of the three gas-filled balloons. Rank the buoyant force from greatest to least.Rank the amount of force the right-hand piston can lift, from greatest to least.Stand on a bathroom scale and read your weight. When you lift one foot up so that you are standing on one foot, does the reading change? Does a scale read force on pressure?In a deep dive, a whale is appreciably compressed by the pressure of the surrounding water. What happens to the whales density?A balloon is weighted so that it is barely able to float in water. If it is pushed beneath the surface, will it rise back to surface, stay at the depth to which it is pushed, or sink? Explain. (Hint: Does the balloons density change?)The density of the rock doesnt change when it is submerged in the water. Does your density change when you are submerged in deep water? Defend your answer.5TESuppose you wish to lay a level foundation for a home on hilly and bushy terrain. How can you use a garden hose filled with the water to determine equal elevations for distant points?7TEIf the liquid pressure were the same at all depths, would there be a buoyant force on an object submerged in the liquid? Explain.Why is it inaccurate to say that heavy objects sink and that light objects float? Give exaggerated examples to support your answer.Compared to an empty ship, would a ship loaded with a cargo of Styrofoam sink deeper into water or rise in water? Defend your answer.A barrage filled with scrap iron is in a canal lock. If the iron is thrown overboard, does the water level at the side of the lock rise, fall or remain unchanged? Explain.A ship sailing from the ocean into freshwater harbor sinks slightly deeper into the water. Does the buoyant force on it change? If so, does it increase or decrease.Suppose you are given the choice between two life preserver that are identical in size, the first a light one filled with Styrofoam and a second a very heavy one filled with lead pellets. If you submerges these life preservers in the water, upon which will the buoyant force be greater? Upon which will the buoyant force be ineffective? Why are your answers different?A half-filled bucket of water is on a spring scale. Will the reading of scale increase or remain the same if a fish is placed in the bucket? Will your answer be different if the bucket is initially filled to the brim?There is much concern about rising sea level due to melting of ice in the polar regions. What happens to sea levels when enormous blocks of ice presently on land slip into the ocean?Your friend says that the buoyant force of the atmosphere on an elephant is significantly greater than buoyant force of the atmosphere on a small helium-filled balloon? What do you say?When you replace helium in a balloon with hydrogen, which is less dense, does the buoyant force on the balloon change if the balloon remains the same size? Explain.18TE19TEWhat physics principle underlies the following three observations? When passing an oncoming truck on the highway, your car tends to sway toward the truck. The canvas roof of a convertible automobile bulges upward when the car is travelling at high speeds. The windows of older passenger trains sometimes break when a high-speed train passes by on the next track.Suppose that you balance a 5-kg ball on the tip of your finger, which has an area of 1cm2. Show that the pressure on your finger is 50N/cm2, which is 500kPa.A 6-kg piece of metal displaces 1L of water when submerged. Show that its density is 6000kg/m3. How does this compare with the density of water?A 1-kg rock suspended above water weighs 10 N. When the rock is suspended beneath the surface of the water, the scale reads 8 N . (a) What is the buoyant force on the rock? (b) If the container of water weighs 10 N on the weighting scale, what is the scale reading when the rock is suspended beneath the surface of the water? (c) What is the scale reading when the rock is released and rests at the bottom of the container?A merchant in Katmandu sells you a solid-gold 1-kg statue for a very reasonable price. When you get home, you wonder whether or not you got a bargain, so you lower the statue into a container of water and measure the volume of displaced water. Show that, for pure gold, the volume of water displaced will be 51.8cm3.In the hydraulic pistons shown in the sketch, the small piston has diameter of 2 cm; the large piston has a diameter of 6 cm . How much more force can the larger piston exert compared with the force applied to the smaller piston?The wings of a certain airplane have a total surface area of 100m2 . At a particular speed, the difference in air pressure below and above the wings is 4% of atmospheric pressure. Show that the lift on the air-plane is 4 10 5 N .Pumice is a volcanic rock that floats in water. The density of pumice is (a) less than the density of water. (b) equal to the density of water. (c) more than the density of water. (d) But being a rock, it sinks!The pressure at the bottom of a pond does NOT depend on (a) the acceleration due to gravity. (b) water density. (c) the depth of the pond. (d) the surface area of the pond.A completely submerged object always displaces its own (a) weight of fluid. (b) volume of fluid. (c) density of fluid. (d) All of these.A rock suspended by a weighing scale weighs 5N out of water and 3N when submerged in water. What is buoyant force on the rock? (a) 3N (b) 5N (c) 8N (d) None of these.A block of wood with a flat rock tied to its top floats in a bucket of water. If the wood and rock are turned over so the rock is submerged beneath the wood, the water level at the side of the bucket (a) rises. (b) falls. (c) remains the same. (d) But with the rock beneath the wood, both rock and wood sink.In a vacuum, an object has no (a) buoyant force. (b) mass. (c) weight. (d) All of these.Consider two mercury barometer, one having a cross-sectional area of 1 cm 2 and the other 2 cm 2 . Mercury in the smaller tube will rise (a) to the same height as the other. (b) twice as high as the other. (c) four times as high as other. (d) None of these.In a hydraulic press operation, it is impossible for the (a) output piston to move farther than the input piston. (b) force output to exceed the force input. (c) output piston's speed to exceed the input pistons speed. (d) energy output to exceed energy input.The flight of a blimp best illustrates (a) Archimedes principle. (b) Pascals principle. (c) Bernoullis principle. (d) Boyles law.Wind speeding up as it blows over the top of a hill (a) increases atmospheric pressure there. (b) decreases atmospheric pressure there. (c) doesnt affect atmospheric pressure there. (d) brings atmospheric pressure to zero.Why does a penny become warmer when struck by a hammer?What are the temperatures for freezing water on the Celsius and Fahrenheit scales? For boiling water at sea level?What is meant by the statement a thermometer measures its own temperature?4RQ5RQDistinguish between temperature and heat.Is cold the opposite of thermal energy or the lack of it?.Distinguish between a joule and acalorie.Does a substance that heats up quickly have a high or a low specific heat capacity?10RQWhy does a bimetallic strip bend with changes in temperature?When the temperature of ice-cold water is increased slightly, does it undergo a net expansion or net contraction?At what temperature do the combined effects of contraction and expansion produce the smallest volume for water?What is the explanation for a barefoot firewalker being able to walk safely on red-hot wooden coals?Does a good insular prevent heat from getting through it, or does it simply slow its passage?What happens to the temperature of air when it expands?Why does the direction of coastal winds changes from day to night?How does the frequency of radiant energy relate to the absolute temperature of the radiating source?What is terrestrial radiation? How does it differ from solar radiation?Is energy added, or is it released, when boiling water is changed to steam?Which is greater, an increase in temperature of 1 Celsius degree or an increase of 1 Fahrenheit degree? 1 Celsius degree or an increase of 1 Kelvin?3TE4TEWhy will a watermelon stay cool for a longer time than sandwiches when both removed from a cooler on a hot day?Iceland, so named to discourage conquest by expanding empires, is not at all ice-covered like Greenland and parts of Siberia, even though it is nearly on the Arctic Circle. The average winter temperature of Iceland is considerably higher than regions at the same latitude in eastern Greenland and central Siberia. Why is this so?If the winds at the latitude of San Francisco and Washington, D.C., were from the east rather than from the west, why might San Francisco be able to grow only cherry trees and Washington, D.C., only palm trees?An old remedy for a pair of nested drinking glasses that stick together is to run water at different temperatures into the inner glass and over the surface of the outer glass. Which water should be hot, and which cold?A metal ball is just able to pass through a metal ring. When the ball is heated, however, it will not pass through the ring. What would happen if the ring, rather than the ball, were heated? Does the size of the hole increase, stay the same or decrease?10TEState whether water at the following temperatures will expand or contract when warmed a little: 0C;4C;6C.Why is it important to protect water pipes so they dont freeze?If you hold one end of a metal nail against a piece of ice, the end in your hand soon becomes cold. Does cold flow from the ice to your hand? Explain.Many tongues have been injured by licking a piece of metal on a very cold day. Why would no harm result if a piece of wood were licked on the same day even when it has the same temperature?15TE16TEWhat determines whether an object is a net emitter or a net absorber of radiant energy?You can comfortably hold your fingers close beside a candle flame, but not very close above the flame. Why?In a mixture of hydrogen and oxygen gases at the same temperature, which molecules move faster? Defend your answer, and compare it to the fact that if a mouse and a cat run with the same kinetic energy, the mouse runs faster.Water vapor changes phase when it changes into snow. Does this change of phase tend to warm or to cool the surrounding air?What would be the final temperature of a mixture of 50 gram 20C of water and 50 g of 40C water?(Challenge!) Consider a 40,000km steel pipe that forms a ring to fit snuggly all around the circumference of the world. Suppose people along its length breathe on it so as to raise its temperature 1C. The pipe gets longer. It also is no longer snug. How high does it stand above ground level? (To simplify, consider only expansion of its radial distance from the center of the Earth, and apply the geometry formula that relates circumference C and radius r :c=2r. The result is surprising!)Temperature is generally proportional to a substances (a) thermal energy. (b) vibrational kinetic energy. (c) average translational kinetic energy. (d) rotational kinetic energy.2RATWater freezes at a temperature of (a) 0C (b) 273K. (c) Both of these. (d) None of these.Heat is simply another word for (a) temperature. (b) thermal energy. (c) thermal energy that flows from hot to cold. (d) All of these.To say that water has a high specific heat capacity is to say that water (a) requires a lot of energy in order to increase in temperature. (b) gives off a lot of energy in cooling. (c) absorbs a lot of energy for a small increase in temperature. (d) All of theseA bimetallic strip used in thermostats relies on the fact that different metals have different (a) specific heat capacities. (b) thermal energies at different temperatures. (c) rates of thermal expansion. (d) All of these.The density of water at 4C will slightly increase when it is (a) cooled. (b) warmed. (c) Both. (d) Neither.A firewalker walking barefoot across hot wooden coals depends on wood's (a) good conduction. (b) poor conduction. (c) low specific heat capacity. (d) low radiation.Thermal convection is linked mostly to (a) radiant energy. (b) fluids. (c) insulators. (d) All of these.A high-temperature source radiates relatively (a) short wavelength. (b) long wavelength. (c) low frequencies of radiation. (d) None of these.Which part of an atom is positively charged and which part is negatively charged?How does the charge of one electron compare with that of another electron?3RQWhat is meant by the charge is conserved?How is Coulombs law similar to Newtons law of gravitation? How is it different?How does an electrically polarized object differ from an electrically charged object?Why do electrons rather than protons make up the flow of charge in a metal wire?How much energy is given to each coulomb of charge passing through a 6-V battery?Does electric charge flow across a circuit or through a circuit? Does voltage flow across a circuit or is it impressed across a circuit? Explain.Which has the greater resistance, a thick wire or thin wire for same length?When the voltage across the ends of a piece of the wire is doubled, what effect does this have on the current in the wire?When the resistance of a circuit is doubled and no other changes occur, what effect does this have on the current in the circuit?What is the function of the third prong on the plug of an electric appliance?Distinguish between the ac and dc.Does a battery produce dc or ac? Does the generator at the power station produce dc or ac?Which draws more current, a 40-W bulb or 100-W bulb?In a circuit consisting of two lightbulbs connected in series, if the current through the one bulb is 1A, what is the current through the other bulb?In a circuit consisting of two lightbulbs connected in parallel, if there is 6V across one bulb, what is the voltage across the other bulb?How does the total current through the branches of a parallel circuit compare with the current through the voltage source?Are household circuits normally wired in series or parallel?Calculate the current in the 240- filament of a lightbulb connected to a 120-V line.Calculate the current in a toaster that has a heating element of 15 when connected to a 120-V outlet.Calculate how much current warms your feet from electric shocks that have a 90- heating element powered by a 9-V battery.Calculate the current that moves through your fingers (resistance 1000) when you touch them to the terminals of a 6-V battery.Calculate the power of device that carries 0.5 A when impressed with 120 V.Calculate the power of hair dryer that operates on 120 V and draws a current of 10 A.Shown below are three separate pair of point charges. Assume the pairs only interact with each other. Compare and rank the magnitudes of the forces between each pair from highest to lowest order.Compare the circuit below according to the brightness of the bulbs. Rank them from brightest to dimmest. (Or, do they have same brightness?)Rank the current in three lightbulbs and the current in the battery, from greatest to least.Rank the current in three branches and the current in battery, from greatest to least.When combining the fur of a cat, electrons transfer from its fur onto the comb. Is the cats fur then positively or negatively charged? How about the comb?If electron were positive and protons were negative, would Coulombs law be written the same or differently?The 5000 billion freely moving electrons in a penny repel one another. Why dont they fly out of the penny?How does the magnitude of electrical force between a pair of charged objects change when the objects are moved twice as far apart? Three times as far apartHow does the magnitude of electric force compare between a pair of charged particles when they are brought to half their original distance of separation? To one-quarter their original distance? To four times their original distance? (What law guides your answers)?Two equal charges exert equal forces on each other. What if one charge has twice the magnitude of the other. How do the forces they exert on each other compare?When a car is moved into a painting chamber, a mist of paint is sprayed around it. Then the body of the car is given a sudden electric charge and the mist of paint is attracted to it and presto-the car is quickly and uniformly painted. What does the concept of polarization have to do with this?What happens to the brightness of light emitted by a lightbulb when the current that flows in it increases?Your tutor tells you that an ampere and a volt really measure the same thing, and the different terms only serve to make a simple concept seem confusing. Why should you consider getting a different tutor?In which of the circuit below does a current exist to light the bulb?Does more current flow out of a battery than into it? Does more current flow into a lightbulb than out of it? Explain.Only a small percentage of the electric energy going into a common lightbulb is transformed into light. What happens to the rest?Why are thick wires rather than thin wires usually used to carry large current?What is the effect on current in a wire if both the voltage across it and its resistance are doubled? If both are halved?Will the current in a lightbulb connected to a 220-V source be greater or less than when the same bulb is connected to a 110-V source?Which will do less damage-plugging a 110-V appliance into a 220-V circuit or plugging a 220-V appliance into a 110-V circuit? Explain.The damaging effects of electric shock result from the amount of current that flows in the body. Why, then, do we see signs that read "Danger - High Voltage" rather than "Danger - High Current"?If several bulbs are connected in series to a battery, they may feel warm to the touch but not visibly glow. What is your explanation?In the circuit shown, how does the brightness of each identical lightbulbs compare? Which bulb draws the most current? What will happen if bulb A is unscrewed? If C is unscrewedAs more and more bulbs are connected in series to flashlight battery, what happens to the brightness of each bulb? Assuming heating inside the battery is negligible, what happens to the brightness of each bulb when more and more are connected in parallel?Two point charges are separated by 6cm. The attractive force between them is 20N. Find the force between them when the distance between them is 12cm. (Why can you solve this problem without knowing the magnitudes of the charges?)Make use of Coulombs law here. Suppose you have a pair of electrically charged metal spheres suspended a certain distance from each other by insulating threads. There is a specific amount of electrical forces between them, (a) If the charge on the one sphere were doubled, what would happen to the force between them? (b) If the charge on the two spheres were doubled, what would happen to the force between them? (c) If the distance between the two spheres were tripled, what would happen to the force between them? (d) If the distance between the two spheres were reduced to one fourth, what would happen to the force between them? (e) If the charge on the one sphere were doubled and the distance between them were doubled, what would happen to the force between them?A radio speaker has a resistance of 8 . Show that when 12V is impressed across the speaker, the current is 1.5A .Rearrange the equation current = voltage/resistance to express resistance in terms of current and voltage. Then consider the following: A certain device in a 120V circuit has a current rating of 20A . show that the resistance of the device is 6 .What is the effect on current through a circuit of steady resistance when the voltage is doubled? What if both voltage and resistance are doubled?Begin with the definition of power (current x voltage) and then show that the current in a 6W clock radio operating in a common 120V circuit is 0.05A .When you brush your hair and scrape electrons from your hair the charge of your hair becomes (a) positive. (b) negative. (c) Actually both of these. (d) Actually neither of these.According to Coulombs law, a pair of particles that are placed twice as close to each other will experience forces (a) twice as strong. (b) four times as strong. (c) half as strong. (d) one-quarter as strong.When you buy a water pipe in a hardware store, the water isnt included. When you buy copper wire, electrons (a) must be supplied by you, just as water must be supplied for a water pipe. (b) are already in the wire. (c) may fall out, which is why wires are insulated. (d) None of these.To receive an electric shock, there must be (a) current in one direction. (b) moisture in an electrical device being used. (c) high voltage and low body resistance. (d) a difference in potential across part or all of your body.A 10- resistor carries 10A. The voltage across the resistor is (a) zero. (b) more than zero but less than 10V. (c) 10V. (d) more than 10V.You can touch and discharge a 10,000-V Van de Graaff generator with little harm because, although the voltage is high, there is relatively little (a) resistance. (b) energy. (c) grounding. (d) All of these. (e) None of these.Compared with the amount of current in the filament of a lamp, the amount of current in the connecting wire is (a) definitely less. (b) often less. (c) actually more. (d) the same. (e) Incredibly, all of these.As more lamps are connected to a series circuit, the overall current in the power source (a) increases. (b) decreases. (c) remains the same.As more lamps are connected to a parallel circuit, the overall current in the power source (a) increases. (b) decreases. (c) remains the same.The difference between dc and ac in electrical circuits is that in dc (a) charges flow steadily in one direction only. (b) charges flow in one direction. (c) charges steadily flow to and fro. (d) charges flow to and fro.1RQ2RQAn electric field surrounds an electric charge. What additional field surrounds a moving electric charge?What two kinds of motion are exhibited by the electrons in an atom?5RQ6RQ7RQWhat happens to the direction of the magnetic field about an electric current when the direction of the current is reversed?In what direction relative to a magnetic field does a charged particle move in order to experience maximum deflecting force? Minimum deflecting force?Both gravitational and electrical forces act along the direction of the force fields. How is the direction of the magnetic force on a moving charge different?11RQWhat happens to the direction of the force on a wire when the current in it is reversed?What is a galvanometer called when calibrated to read current? Voltage?What must change in order for electromagnetic induction to occur?What are the three ways that voltage can be induced in a wire?What is the basic difference between a generator and an electric motor?What is the basic similarity between a generator and an electric motor?What commonly supplies the energy input to a turbine?What is induced by the rapid alteration of a magnetic field?What is induced by the rapid alternation of an electric field?Rank from most to least the reading on the galvanometer. Most current___ ___ ___ Least current or, induced current the same for each.___Make the same ranking, only this time for each coil having twice as many as loops as in Question 1.A paper clip near the north pole of a magnet is attracted to the magnet. Will the paper clip be attracted to the south pole of the magnet? Explain.What is different about the magnetic poles of common refrigerator magnets compared with common bar magnets?What surrounds a stationary electric charge? A moving electric charge?"An electron always experiences a force in an electric field, but not always in a magnetic field." Defend this statement.Cans of food in your kitchen pantry are likely magnetized. Why?A friend tells you that a refrigerator door, beneath its layer of white painted plastic, is made of aluminum. How could check to see if this is true (without any scraping)?Magnet A has twice the magnetic field strength of magnet B (at equal distance) and at a certain distance pulls on magnet force with a force of 50N.With how much force, then, does magnet B pull on magnet A?