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All Textbook Solutions for Conceptual Physical Science Explorations
What discovery in the 15th century greatly advanced progress in science?Throughout the ages, how have most people responded to new ideas: with acceptance or resistance?Why is mathematical problem solving not a major feature of this book?In this book, which comes first: comprehension or calculation?Outline the steps of the scientific method.Distinguish among a scientific fact, a hypothesis, a law and a theory.How many experiments are necessary to invalidate a scientific hypothesis?Must a statement prove correct to be a scientific hypothesis?In science, what kind of ideas are generally accepted?Why is honesty a matter of self-interest to a scientist?Why are students of the arts encouraged to learn about science, and science students encouraged to learn about the arts?How do scientists regard “not knowingâ€� in general?Clearly distinguish between science and technology.14RQName at least two fields of scientific study in the physical sciences and two from the life sciences.In daily life, people are often praised for maintaining some particular point of view, for the “courage of their convictionsâ€�. A change of mind is seen as a sign of weakness. How is this different in science?In daily life, we see many cases of people who are caught misrepresenting things and who soon thereafter are excused and accepted by their contemporaries. How is this different in science?In answer to the question “When a plant grows, where does the material come from?â€� Aristotle hypothesized by logic that all material came from the soil. Do you consider his hypothesis to be correct, incorrect or partially correct? What experiments do you propose to support your choice?What is probably being misunderstood by a person who says, “But that’s only a scientific theoryâ€�?(a) Make an argument for bringing to a halt the advances of technology. (b) Make an argument that advances in technology should continue. (c) Contrast your two argyumenets.According to Aristotle, where do moving objects tend to reach?According to Aristotle, what kind of motion requires no force?What two of Aristotle's main ideas did Galileo discredit?What is the name of the property of objects to maintain their states of motion?Distinguish between speed and velocity.Why do we say velocity is a vector quantity and speed is not?How can you both at rest and also moving at 100,000km/h at same time?Was it Aristotle or Galileo who relied on experiments?Who was first to discover the concept of inertia, Galileo or Newton? Who incorporated it into law of motion?What is the tendency of a moving object when no forces act on it?When only a pair of equal and opposite forces act on an object, what is the net force acting on it?We’ve learned that velocity is a vector quantity. Is force also a vector quantity? Why or why not?Name the force that occurs in a rope when both ends are pulled in opposite directions.How much tension is there in a rope that holds a 20N bag of apples at rest?What is the meaning of F=0?Why is the support force on an object often called the normal force?When you weigh yourself, are you actually reading support force acting on you, or are you really reading you weight?Give an example of something moving when a net force of zero acts on it.If we push a crate at constant velocity, how do we know how much friction acts on the crate compared to our pushing force?If you’re in a smooth-riding bus that is going at 50km/h and and you flip a coin vertically, what is the horizontal velocity of the coin in midair?Calculate Emily’s average walking speed when she covers 1meter in 0.5second.Calculate your average speed if you run 100 meters in 10 seconds.Calculate the average speed of a mouse who runs across a 4-meter-long room in 0.4 seconds.Calculate the speed of a bowling ball that moves 8 meters in 4 seconds.Jogging Johnny runs along a train flatcar that moves at the velocities shown. From greatest to least,rank the relative velocities of Jake as seen by an observer on the ground. (Call the direction to the right positive).A track is made of a piece of channel metal bent as shown. A ball is released from rest at the left end of the track and continues past the various points. Rank the ball at points A, B, C, and D, from fastest to slowest. (Watch for tie scores.)A block of iron is suspended by ropes in the positons shown below. Scales measure the tension (stretching force) in the ropes. Rank the scale reading from greatest to least.Galileo found that a ball rolling down one incline will pick up enough speed to rollupanother. How high will it roll compared with its initial height?Correct your friend who says, "The race-car driver rounded the curve at a constant velocity of 100km/h."If the speedometer of a car reads a constant speed of 50km/h , can you say that the car has a constant velocity? Why or why not?A hungry mosquito watches you resting in a hammock in a 3-m/s breeze. With what velocity relative to the air should the mosquito hover above you for lunch?If a huge bear were chasing you, its enormous mass would be very threatening. But if you ran in a zigzag pattern, the bears mass would be to your advantage. Why?A space probe may be carried by a rocket into outer space. Your friend asks what kind of force keeps the probe moving after the rocket no longer pushes it. What is your answer?Consider a ball at rest in the middle of a toy wagon. When the wagon is pulled forward, the ball rolls to the back of the wagon. Interpret this observation in terms of Newtons first law.Why do you lurch forward in a bus that suddenly slows Why do you lurch backward when it picks up speed? What law applies herePush a shopping cart and it moves. When you stop pushing, it soon comes to rest. Does this violate Newtons law of inertia? Defend your answer.When your car moves along the highway at constant velocity, the net force on it is zero. Why, then, do you continue running your engine? (Hint: How does friction enter into your answer?)Consider a pair of parallel forces, one having a magnitude of 20N, and the other 12N. What maximum net forceis possible for these two forces? What is the minimum net forcepossible?The sketch shows a painting scaffold in mechanical equilibrium. The person in the middle weighs 250N, and the tensions in each rope are 200N. What is the weight of the scaffold?A different scaffold that weighs 300N supports two painters, one of whom weighs 250N and the other 300N. The reading on the left scale is 400N. What is the reading on the right-hand scale?Nellie Newton hangs at rest from the ends of the rope, as shown. How does the reading on the scale compare to her weight?Harry the painter swings year after year from his bosun’s chair. His weight is 500N and the rope, unknown to him, has a breaking point of 300N. Why doesn’t the rope break when he is supported as shown at the left below? One day Harry is painting near a flag pole, and for a change he ties the free end of the rope to the flagpole instead of to his chair, as shown at the right. Why did Harry end up taking his vacation early?Latisha stands on a bathroom scale and reads her weight. Does the reading change if she raises one foot on the scale? How about if she stands with one foot on the scale and the other foot on the floor?A child learns in school that Earth is travelling faster than 100000km/h around the Sun and in a frightened tone asks why we arent swept off. What is your explanation?If you toss a coin straight upward while riding in a train, where does the coin land when the motion of the train is uniform along a straight-line track? When the train slows while the coin is in the air? When the train is turning?As Earth rotates about its axis, it takes 3 hours for the United States to pass beneath a point above Earth that is stationary relative to the sun. What is wrong with the following scheme? To travel from Washington D.C. to San Francisco and use very little, simply ascend in a helicopter high over Washington D.C. and wait 3 hours until San Francisco passes below.A tennis ball travels the full length of the court, 24m , in 0.5s . What is the average speed?What is your average speed if you run 50m in 10s? Show that the distance you’d travel at this speed for 1minute would be 300m.Find the net force produced by a 30-N and 20-N force in each of the following cases: (a) Both forces act in the same direction. (b) Both forces acts in opposite directions.A horizontal force of 100N is required to push a crate of cell phones across a floor at a constant speed. (a) What is the net force acting on the crate? (b) What is the force of friction acting on the crate?Phil Physicer weighs 600N(132lb) and stands on two bathroom scales. He stands so one scale reads twice as much as the other. What are the scale readings?Aristotle distinguished between natural motion and unnatural motion. Galileo stated that all motion (a) is natural. (b) is unnatural. (c) follows the same laws. (d) is an illusion.The difference between speed and velocity most involves (a) direction. (b) amount. (c) different unit. (d) acceleration.The first scientist to discover the concept of inertia was (a) Aristotle. (b) Galileo. (c) Newton. (d) Einstein.According to Newtons first law of motion (a) objects at rest tend to remain at rest. (b) objects in motion tend to remain in motion. (c) Both of these. (d) None of these.A ball rolling along a bowling alley moves at constant speed (a) without the need of horizontal force. (b) due to a slight force in its direction of motion. (c) due to slight friction that slows it. (d) due to gravity.If your textbook is pulled to the right with while being pulled to the left with , the net force on the book is (a) to the left. (b) to the right. (c) to the right. (d) None of these.The equilibrium rule, F=0 , applies to (a) objects or systems at rest. (b) objects or systems in uniform motion in a straight line. (c) both of these. (d) none of these.When you stand on two bathroom scales, one foot on each scale with weight evenly distributed, each scale will read (a) your weight. (b) half your weight. (c) zero. (d) actually more than your weight.If you push your desk along the floor with a force of 80 N and it slides at constant speed, then the force of friction acting on the desk is (a) also 80 N in the direction of your push. (b) 80 N in the direction opposite to your push. (c) zero. (d) None of these.Suppose you stand on the floor of a train moving at constant speed in a straight line. If you jump straight upward, you will land (a) at your original location (b) slightly in front of your original location. (c) slightly in back of your original location. (d) in back of your original location a distance that depends on how high you jump.Distinguish between velocity and acceleration.When are you aware of motion in a moving vehicle--- when it is moving steadily in a straight line or when it is accelerating?What is the acceleration of free fall?Is acceleration proportional to net force or does acceleration equal net force?What relationship does mass have to inertiaWhat relationship does mass have to weight?Fill in the blanks: Shake something to and fro and you’re measuring its _____. Lift it against gravity and you’re measuring its _____.What is the weight of a brick?Is acceleration directly proportional to mass, or is it inversely proportional to mass? Give an example.10RQIf the mass of a sliding block is somehow tripled at the same time the net force on it is tripled, how does the resulting acceleration compare to the original acceleration?Suppose you exert a horizontal push on a crate that rests on a level floor and it doesn’t move. How much friction acts compared with your push?As you increase your push, will friction on the crate increase also?Once the crate is sliding, how hard do you push to keep it moving at constant velocity?What is meant by free fall?Why doesnt a heavy object accelerate more than a light object when both are freely fallingThe ratio of circumference/diameter for all circles is . What is the ratio of force/mass for freely falling objects?What two principal factors affect the force of air drag on a falling object?What is the acceleration of a falling object when it reaches its terminal velocity?If two objects of the same size fall through air at different speeds, which encounters the greater air drag?Calculate the acceleration of a ball rolling down a hill that gains of 4m/s in 2s.Calculate the acceleration of a bike that goes from to in .Calculate the acceleration of a crate of softball gear when pulled sideways with a net force of .Calculate the acceleration of a , single-engine airplane just before takeoff when the thrust of its engine is.Compare from greatest to least, the accelerations of these objects: (a) Net force 20N acts on a mass of 10kg . (b) Net force 30N acts on a mass of 18kg . (c) Net force 40N acts on a mass of 30kg . (d) Net force 50N acts on a mass of 32kg . Greatest ___ ___ ___ ___ LeastBoxes of chocolates of various masses on a friction-free level table. Compare from greatest to least: (a) The net forces on the boxes. Greatest ___ ___ ___ ___ Least (b) The acceleration of the boxes. Greatest ___ ___ ___ ___ Least.Compare from greatest to least the accelerations of these skydivers. (a) man with of air drag. (b) woman with of air drag. (c) woman with of air drag. (d) dog with of air drag. Greatest ___ ___ ___ ___LeastWhat is the net force on a bright red Mercedes convertible traveling along a straight road at a steady speed of 100km/hOn a long alley a bowling ball slows down as it rolls. Is any horizontal force acting on the ball? How do you know?In the orbiting space shuttle you are handed two identical boxes, one filled with sand and the other filled with feathers. How can you tell which is which without opening the boxes?In the orbiting space shuttle you are handed two identical boxes, one filled with sand and the other filled with feathers. How can you tell which is which without opening the boxes?What happens to your weight when you mass increases?When a junked car is crushed into a compact cube, does its mass change? Its weight? Its volume? ExplainWhat is the net force on a apple when you hold it at rest above your head? What is the net force on the apple after you release it?On which of these hills does the ball roll down with increasing speed and decreasing acceleration along the path? (Use this example if you wish to explain to someone the difference between speed and acceleration.)9TEA bear that weights grasps a vertical tree and slides down at constant velocity. What is the friction force that acts on the bear?11TEWhat is the acceleration of a ball at the top of its trajectory when thrown straight upward? Explain whether or not your answer is zero by the using the equation a=F/m as a guide to your thinking. (Interesting, almost everyone gets the wrong answer unless they choose F to be mg and let Newtons second law guide their thinking! Use this question if youre helping someone make the distinction between speed and acceleration.)Aristotle claimed the speed of a falling object depends on its weight. We now know that objects in free fall, whatever their weights, undergo the same gain in speed. Why does weight not affect acceleration?Two pumpkins are dropped from a high building through the air. One pumpkin is hollow and the other is filled with rocks. Which accelerates more? Defend your answer.In a vacuum, a coin and a feather fall equally, side by side. Would it be correct to say that in a vacuum equal forces of gravity act on both the coin and the feather? Defend your answer.How does the force of gravity on a raindrop compare with the air drag it encounters when it falls at constant velocity?Upon which will air drag be greater; a sheet of falling paper or the same paper wadded into a ball that falls at a faster terminal speed?(Careful!)Why is it that a cat that accidentally falls from the top of a 50-story building hits the safety net below no faster than if it falls from the 20th story?How does the terminal speed of a parachutist before opening a parachute compare with terminal speed after? Why is there a difference?How does the gravitational force on a falling body compare with the air drag it encounters before it reaches terminal velocity? After?One pound is the same as 4.45 newtons. What is the weight in pounds of 1 newton?Consider a 40-kg block of cement when pulled sideways with a net force of 200N. Show that its acceleration is 5m/s2Consider a mass of 1kg accelerated 1m/s2 by a force of 1N. Show that the acceleration would be the same for 2kg acted on by a force of 2N.Consider a jumbo jet of mass 30,000kg in takeoff when the thrust form each of four engines is 30,000N. Show that its acceleration is 4m/s2.Leroy, who has a mass of is skateboarding at when he smacks into a brick wall and comes to a dead stop in . (a) Show that his deceleration is . (b) Show that the force of impact is . (ouch!)Consider a ball that picks up a speed of 2m/s. each second when it rolls from rest down an inclined plane. If the ball takes 5 seconds to reach the bottom, its speed at the bottom will be (a) 5m/s. (b) 7.5m/s. (c) 10m/s. (d) None of the above.When the ball rolls down the inclined plane in the previous question, as its speed increases its acceleration (a) increases. (b) decreases. (c) remains unchanged.An object in free fall undergoes an increase in (a) speed. (b) acceleration. (c) both speed and acceleration.An object with a huge mass also must have a huge (a) weight. (b) volume. (c) size. (d) surface area.If gravity between Sun and Earth suddenly vanished, Earth would continue moving in (a) a curved path. (b) a straight-line path. (c) an outward spiral path. (d) an inward spiral path.A heavy rock and a light rock in free fall have the same acceleration. The reason the heavy rock does not have more acceleration is (a) the force of gravity on each is the same. (b) there is no air resistance. (c) the inertia of both rocks is the same. (d) All of these. (e) None of theseWhen a falling object encounters of air resistance, its acceleration is (a) less than g. (b) g. (c) more than g. (d) Not enough information.The amount of air resistance on a 0.8-N flying squirrel for terminal speed is (a) less than 0.8-N. (b) 0.8-N. (c) more than 0.8-N. (d) dependent on the orientation of its body.If you drop at the same time a regular soccer ball and a soccer ball filled with sand from the top of a tall building, the ball to land first will be, (a) regular soccer ball. (b) ball filled with sand. (c) They will hit at the same timeThe scientist who found the connection between force, mass and acceleration was (a) Galileo. (b) Newton. (c) Both (d) Neither.In the simplest sense, a force is a push or pull. In a deeper sense, what is a force?How many forces are required for interaction? How many forces are required for interaction?When you push against a wall with your fingers, they bend because they experience a force. Identify this force. When you push against a wall with your fingers, they bend because they experience a force. Identify this force.Why do we say a speeding object doesnt possess force?State Newtons third law of motion.Consider hitting a baseball with a bat. If we call the force on the bat against the ball the action force, identify the reaction force.If a bat hits a ball with 1000N of force, with how much force does the ball, hit back on the bat?If the world pulls you downward, what is the reaction force?If the forces that act on a cannonball and the recoiling cannon from which it is fired are equal in magnitude, why do the cannonball and cannon have very different accelerations?Identify the force that propels a rocket.When can the net force on a ball be zero when you kick it?Why do the interatomic forces inside a ball not accelerate the ball?Referring to Figure 4.13, how many forces are exerted on the cart? What is the horizontal net force on the cart?How many forces are exerted on the horse? What is the net force on the horse?How many forces are exerted on the horse-cart system? What is the net fore on the horse-cart system?Which is most important in winning a tug-of-war-pulling harder on the rope, or pushing harder on the floor?How does a helicopter get its lifting force?A boxer can hit a heavy bag with great force. Why cant he hit a sheet of newspaper in midair with the same amount of force?Can you physically touch another person without that person touching you with the same amount of force?Fill in the blanks: Newtons first law is often called the law of ______; Newtons second law highlights the concept of ______; and Newtons third law is the law of ______ and ______.The photo shows Steve Hewitt and daughter Gretchen. Is Gretchen touching Dad, or is Dad touching her? Explain.For each of the following interactions, identify action and reaction forces (a) A hammer hits a nail. (b) Earth gravity pulls down on you. (c) A helicopter blade pushes air downward. For each of the following interactions, identify action and reaction forces (a) A hammer hits a nail. (b) Earth gravity pulls down on you. (c) A helicopter blade pushes air downward.You hold an apple over your head. (a) Identify all the forces acting on the apple and their reaction forces. (b) When you drop the apple, identify all the forces acting on it as it falls and the corresponding reaction forces. Neglect air drag. You hold an apple over your head. (a) Identify all the forces acting on the apple and their reaction forces. (b) When you drop the apple, identify all the forces acting on it as it falls and the corresponding reaction forces. Neglect air drag.Identity the action-reaction pairs of forces for the following situations: (a) You set off a curb. (b) You pat your tutor on the back. (c) A wave hits a rocky shore.Consider a tennis player hitting a ball. (a) Identify the action-reaction pairs when the ball is being hit and (b) while the ball isin flightA small car bumps into a van at rest in a parking lot. Upon which is the force of contact greater? Which vehicle undergoes the most acceleration? Defend your answer.Your teacher challenges you and your best friend to pull on a pair of scales attached to the ends of a horizontal rope, in tug-of-war fashion. Can you each pull in such a way that the readings on the scales will differ? Defend your answer.You push a heavy car by hand. The car, in turn, pushes back with an opposite but equal force on you. Doesnt this mean the forces cancel one another, making acceleration impossible Why or why notA farmer urges his horse to pull a wagon. The horse refuses, saying to try would be futile for it would contradict Newtons third law. The horse concludes that she cant exert greater force on the wagon than the wagon exert on her, and therefore wont be able to accelerate the wagon. What is your explanation to convince the horse to pull?Suppose two carts, one twice as massive as the other, fly apart when the compressed spring that joins is released. How fast does the heavier cart roll compared to the lighter cart.If you exert a horizontal force of 200N to slide a desk across a classroom floor at constant velocity, how much friction does the floor exert on the desk? Is the force of friction equal and oppositely directed to your 200-N push? If the force of friction isnt the reaction force to your push, what is?If a massive truck and small sports car have a head-on collision, upon which vehicle is the collision force greater? Which vehicle experiences the greater acceleration?Ken and Joanne are astronauts floating some distance apart in space. They are joined by a safety cord, the ends of which are tied around their waists. If Ken starts pulling on the cord, will he pull Joanne toward him, or will he pull himself toward Joanne, or will both astronauts move? Explain.The strong man can withstand the tension force exerted by the two horses pulling in opposite directions. How would the tension compare if only one horse pulled and the left rope were tied to a tree? How would the tension compare if the two horses pulled in the same direction, with the left rope tied to the tree?In a tug-of-war between two physics types, each pulls on the rope with a force of 250N. What is the tension in the rope? If both remain motionless, what horizontal force does each exert against the ground?A stone is shown at rest on the ground. (a) The vector shows the weight of the stone. Complete the vector diagram showing another vector that results in zero net force on the stone.(b) What is the conventional name of the vector you have drawn?Here a stone is suspended at rest by a string. (a) Draw force vectors for all the forces that act on the stone. (b) Should your vectors have a zero resultant? (c) Why, or why not?Suppose the string in the preceding exercise breaks and the stone slows in its upward motion. Draw a force vector diagram of the stone when it reaches the top of its path.What is the acceleration of the stone in Think and Explain 19 at the top of its path?If you apply a net force of 5N on a cart with a mass 5kg, show that the acceleration is 1m/s2.If you increase the speed of a 2.0-kg air puck by 3.0m/s in 4.0s, show that the force you exert on it is 1.5N.A boxer punches a sheet of paper in midair and brings it from rest up a speed of 25m/s in 0.05s. If the mass of the paper is 0.003kg, show that force the boxer exerts on it is only 1.5N (about one-third of 1lb).Joshua has a mass of 60kg and stands next to a wall on a frictionless skateboard. If he pushes the wall with a force of 30N, how hard does the wall push on him Show that Joshua accelerates at 0.5m/s2 away from the wall.A soccer ball is kicked to a 30-m/s speed. While being kicked, the amount of force that the players foot exerts on the ball is (a) less than the amount of force on the foot. (b) the same as the amount of force on the foot. (c) more than the amount of force on the foot. (d) None of these.A batted baseball soaring through the air with negligible air resistance has (a) speed. (b) force. (c) Both of these. (d) None of these.A karate chop delivers a force of 3000N to a board that breaks. The force that acts on the hand during this event is (a) less than 3000N. (b) 3000N. (c) more than 3000N. (d) Not enough information to say.A soccer ball is kicked to a 30-m/s speed. While being kicked, the amount of force that the players foot exerts on the ball is (a) less than the amount of force on the foot. (b) the same as the amount of force on the foot. (c) more than the amount of force on the foot. (d) None of these.When a cannonball is fired from a cannon, both the cannonball and the cannon experience (a) equal amounts of force. (b) equal accelerations. (c) Both of these. (d) None of these.The force that propels a rocket is provided by (a) gravity. (b) Newtons laws of motion. (c) its exhaust gases. (d) the atmosphere against which the rocket pushes.The team that wins in a tug-of-war is the team that (a) produces more tension in the rope than the opponent. (b) pushes hardest on the floor. (c) Both of these. (d) None of these.The net force on a kicked football can be zero when (a) action and reaction both act on the ball. (b) it is kicked by two feet with equal and opposite amounts of force. (c) it is kicked in the same direction by two feet. (d) None of these.The heavyweight boxing champion of the world cant hit a piece in midair with much force because (a) an interaction isnt possible in this case. (b) the paper cant produce much opposite force. (c) the paper is too light in weight. (d) Newtons third law cant occur.Which has a greater momentum, a heavy truck at rest or a moving automobile?How can a supertanker have a huge momentum when it moves relatively slowly?Why is it incorrect to say that impulse equals momentum?To impart the greatest momentum to an object, what should you do in addition to exerting the largest force possible?For the same force, which cannon imparts the greater speed to a cannonball-a long cannon or a short one? ExplainIf youre in a car with faulty brakes and you have to hit something to stop, the momentum will change to zero whether you hit a brick wall or a haystack. So why is hitting a haystack a safer bet?Why is it less damaging if you fall on a mat than if you fall on a solid floor?Why is it a good idea to extend your hand forward when catching a fast-moving baseball with your bare hand?9RQIn karate, why is a short time for the applied force advantageous?Which is the greater change in momentum, stopping something dead in its track or stopping it and then reversing its direction?Which requires the greater impulse, stopping something dead in its tracks or stopping it and then reversing its direction?When can the momentum of two moving objects be canceled?What does it mean to say that momentum (or any quantity) is conserved?When a cannonball is fired, its momentum does change. Is momentum conserved for the cannonball?When a cannonball is fired, the cannon recoils. Is momentum conserved for the cannon?When a cannonball is fired, is momentum conserved for the cannon-cannonball system as a whole? (Why is your answer different than in the previous two questions?)Distinguish between an elastic collision and an inelastic collision. For which type of collision is momentum is momentum conserved?Railroad car A rolls at a certain speed and makes perfectly elastic collision with car B of the same mass. After the collision, car A is observed to be at rest. How does the speed of the car B compare with the initial speed of the car A?If the equally massive cars of the previous question stick together after colliding inelastically, how does their speed after the collision compare with initial speed of the car A?Calculate the momentum of a 10kg bowling ball rolling at 3m/s.Calculate the momentum of a 50-kg carton that slides at 3m/s across an icy surface.Calculate the impulse that occurs when an average force of 10N is exerted on a cart for 5s.Calculate the impulse that occurs when the same force of 10N acts on the cart for twice the time.The balls have different masses and speeds. (a) Rank them in terms of momentum, from greatest to least. (b) Rank them in terms of the impulse needed to stop them, from greatest to least.Evan pushes crate starting at rest across a floor for 4seconds with a net force as shown (including friction). Rank the three situations from biggest to smallest. (a) Change in momentum (b) Final speed (c) Momentum in 4secondsWhen rollerblading, why is a fall less harmful on a wooden floor than on a concrete floor that has less give? Explain in terms of impulse and momentum.In terms of impulse and momentum, why do air bags in cars reduce the chances of injury in accidents?3TEIn terms of impulse and momentum, why are nylon ropes (which stretch considerably under tension) favored by mountain climbers?If you throw an egg against a wall, the egg will break. But if you throw it at the same speed into a sagging sheet, it may not break. Why?A lunar vehicle is tested on Earth at a speed of 10km/h. When it travels as fast on the Moon, is its momentum more, less, or the same?Which has the greater momentum when they move at the same speed-an automobile or a skateboard? Which requires the greatest stopping force?In answering the preceding exercise, perhaps you stated that the automobile requires more stopping force. Make an argument that the skateboard could require more stopping force, depending on how quickly you want to stop it.Why do 6-ounce boxing gloves hit harder than 16-ounce gloves?Which undergoes the greatest change in momentum: (1) a baseball that is caught, (2) a baseball that is thrown, or (3) a base ball has the same speed just before being caught and just after being thrown?In the preceding question, in which case is the greatest impulse required?If a fully loaded shopping cart and an empty one travelling at the same speed have a head-on collision, which cart will experience the greater force of impact? The greater impulse? The greater change in momentum? The greater acceleration?A fully dressed person is at rest in the middle of a pond on perfectly frictionless ice and must get to shore. How can this accomplished?Michael throws a ball horizontally while standing on roller skates. He rolls backward with a momentum that matches that of the ball. Will he end up rolling backward if he goes through the motions of throwing the ball, but instead holds onto it? Explain.Two football players have a head-on collision and both stop short in their paths. If one player is twice as heavy as the other, how does his speed compare to the smaller player?In the previous chapter, rocket propulsion was explained in terms of Newton's third law. That is, the force that propels a rocket is from the exhaust gases pushing against the rocket-the reaction to the force the rocket exerts on the exhaust gases. Explain rocket propulsion in terms of momentum conservation.When you are travelling in a car at highway speed, the momentum of a grasshopper is suddenly changed as it splatters onto your windshield. Compared to change in momentum of the grasshopper, by how much does the momentum of the car change?If an 18-wheeler tractor-trailer and a sports car have an head-on collision, which vehicle will experience greater force of impact? The greater impulse? The greater change in momentum? The greater acceleration?Your friend says that law of momentum conservation is violated when a ball rolls down a hill and gains momentum? What is your response?How much impulse is needed to stop a 10kg bowling ball moving at 6m/s?A car with a mass of 1000kg moves at 20m/s. Show that the braking force needed to bring the car to a halt in 10s is 2000N.A car carrying a 75kg test dummy crashes into a wall at 25m/s and is brought to rest in 0.1s. Show that the average force exerted by the seat belt on the dummy is 18,750N.Jane (mass 40.0kg), standing on the slippery ice, catches her leaping dog (mass 15kg) moving horizontally at 3.0m/s. Show that the speed of the Jane and her dog after the catch is 0.8m/s.A 2kg ball of putty moving to the right has a head-on inelastic collision with a 1kg putty ball moving to the left. If the combined blob doesnt move just after the collision, what can you conclude about the relative speeds of the balls before they collided?A railroad diesel engine weighs four times as much as a freight car. If the diesel engine coasts at 5km/h into a freight car that is initially at rest, show that the speed of the coupled car is 4km/h.7TSA 1kg ostrich egg is thrown at 2m/s at a bedsheet and is brought to rest in 0.2s. Show that the average amount of force on the egg is 10N.If fast Freddy doubles his running speed, what else doubles? (a) His momentum (b) His inertia (c) His time of running (d) His accelerationA 1kg ball has the same speed as a 10kg ball. Compared with 1kg ball, the 10kg ball has (a) one-tenth the momentum (b) the same momentum (c) 10 times as much momentum (d) 100 times as much momentumTwo iron, balls, one twice the mass of other, are dropped from rest from the top of a one- story building. Compared with lighter ball, the twice-as-heavy ball when hitting the ground below has (a)half the momentum (b)the same momentum (c)twice the momentum (d)four times the momentumIf the mass of a cart full of groceries decreases to half and its speed doubles, the momentum of the cart (a) remains unchanged. (b) is doubled. (c) is quadrupled. (a) decreases.Your friend says that the impulse equals momentum. You disagree and say the friend is missing an important word, which is (a) inertia. (b) acceleration. (c) time. (d) change.The impulse-momentum relationship is a direct result of Newton's (a) first law. (b) second law. (c) third law. (d) law of gravity.Which of the following equations best illustrates the usefulness of automobile air bags? (a) a=F/m (b) Ft=mv (c) d=1/2gt2 (d) d=vtWhen you jump from an elevated position to the ground below, the force your experience when landing depends on (a) the jumping height. (b) the softness or hardness of the ground. (c) how much your knees bend. (d) All of the above.Standing on a stakeboard, you toss a ball horizontally away from you. The mass of the ball is one-tenth your mass. Compared with the speed you give to the ball, your ideal recoil speed will be (a) one-tenth as much. (b) the same (c) ten times as much (d) one hundred times as muchA big fish swims upon and swallows a small fish at rest. After lunch, the momentum of the big fish is (a) the same as before. (b) less than before. (c) more than before. (d) zero.A force sets an object in motion. When the force is multiplied by the time of its application, we call the quantity impulse, which changes the momentum of that object. What do we call the quantity forcedistance ?Cite an example where a force is exerted on an object without doing work on the object.Which requires more work-lifting a 50-kg sack a vertical distance of 2m or lifting a 25-kg sack a vertical distance of 4m?If both sacks in the preceding question are lifted their respective distances in the same time, how does the power required for each compare? How about for the case where the lighter sack is lifted its distance in half the time?What are the two main forms of mechanical energy?Exactly what is it that a body having energy is capable of doing?A car is lifted a certain distance in a service station and therefore has potential energy relative to the floor. If it were lifted twice as high, how much potential energy would it have?Two cars are lifted to the same elevation in service station. If one car is twice as massive as the other, how do their potential energies compare?How many joules of potential energy does a 1-N book gain when it is elevated 4m ? When it is elevated 8m ?A moving car hovas kinetic energy. If it speeds up until it is going four times as fast, how much kinetic energy does it have in comparisonCompared to some original speed, how much work must the brakes of a car supply to stop a car moving four times as fast How will thestopping distance compareWhat will be the kinetic energy of a pile driver ram when it undergoes a 10-kJ decrease in potential energy (Assume no energy goes to heat.)Can a machine multiply input force Input distance Input energy (If your three answers are the same, seek help, for the last question is especially important.)If a machine multiplies force by a factor of 4, what other quantity is diminished, and by how muchIf the man in Figure 6.22 pulls of rope downward with a force of 100N , and the load rises 1/7 as high, what is the maximum load that can be liftedWhat is the efficiency of a machine that miraculously converts all the input energy to useful output energyIs a machine that has efficiency greater than 100 physically possible? Discuss.18RQWhat is the source of geothermal energy?The energy we require fro existence comes from the chemically stored potential energy in food, which is transformed into other forms when it is metabolized. What happens to a person whose work output is less than the energy he or she consumes? Whose work output is greater than the energy he or she consumes? Can an undernourished person perform extra work without extra food? Briefly discuss.Calculate the work done when force of 2 N moves a book 2 m .calculate the work done when a 15-N force pushes a cart 3m.Calculate the watts of power expended when a force of moves a book 2m in a time interval of 1s .Calculate the power expended when a 20 N force pushes a cart 3.5 m in a time of 0.5s .How many joules of potential energy does a 1.5kg book gain when it is elevated 2 m ? When it is elevated 4 m ? (Let g = 10 N/kg .)Calculate the increase in potential energy when a 20-kg block of ice is lifted a vertical distance of 3m .Calculate the number of joules of kinetic energy a1-kg parrot has when it flies at 6m/s .Calculate the kinetic energy of a 3-kg dog that runs at a speed of 4m/s .How much work is required to increase the kinetic energy of a motor scooter by 4000J?What change in kinetic energy does a model airplane experience on takeoff if it is moved a distance of 5m by a sustained net force of 10N ?The mass and speed of three vehicles is shown below. (a) Compare the momentum, from most to least. (b) Compare the kinetic energy, from most to least.2TCThe roller coaster starts from rest at point A, then proceeds down the incline. Compare the following for points A-E from most to least. (a) Speed. (b) KE. (c) PE.Consider the efficiency of these four machines: (a) Energy in 100J ; energy out 60J. (b) Energy in 100J ; energy out 50J. (c) Energy in 200J ; energy out 80J. (d) Energy in 200J ; energy out 120J. Compare the efficiencies, from highest to lowest.When the mass of a moving object is doubled with no change in speed, by what factor is its momentum changed? Its kinetic energy?When the velocity of an object is doubled, by what factor is its momentum changed? Its kinetic energy?Consider a ball thrown straight up in the air. At what position is its kinetic energy a maximum? Where is its gravitational potential energy a maximum?At what point in its motion is the KE of a pendulum bob a maximum? At what point is its PE a maximum? When its KE is half its maximum value, how much PE does it have?A physical science teacher demonstrates energy conservation by releasing a heavy pendulum bob, as shown in the sketch, allowing it to swing to-and-fro. What would happen if in his exuberance he gave the bob a slight shove as it left his nose? Explain.Discuss the design of the roller coaster shown in the sketch in terms of the conservation of energy.Suppose that you and two classmates are discussing the design of a roller coaster. One classmate says that each summit must be lower than the previous one. Your other classmate says this is nonsense, for as long as the first one is the highest, it doesnt matter what height the others are. What do you say?Consider a mouse and dog running along a road have the same kinetic energy. Which has the average greater speed? (Use the equation for kinetic energy to guide your thinking.)