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A 50.0-kg student evaluates a weight loss program by calculating the number of times she would need to climb a 12.0-m high flight of steps in order to lose one pound (0.45 kg) of fat.
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Chapter 5 Solutions
COLLEGE PHYSICS V1+WEBASSIGN MULTI-TERM
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Glencoe Physics: Principles and Problems, Student Edition
- Sewage at a certain pumping station is raised vertically by 5.49 m at the rate of 1 890 000 liters each day. The sewage, of density 1 050 kg/m3, enters and leaves the pump at atmospheric pressure and through pipes of equal diameter. (a) Find the output mechanical power of the lift station. (b) Assume an electric motor continuously operating with average power 5.90 kW runs the pump. Find its efficiency.arrow_forwardWater falls over a dam of height h with a mass flow rate of R, in units of kilograms per second. (a) Show that the power available from the water is P=Rgh where g is the free-fall acceleration. (b) Each hydroelectric unit at the Grand Coulee Dam takes in water at a rate of 8.50 105 kg/s from a height of 87.0 m. The power developed by the falling water is converted to electric power with an efficiency of 85.0%. How much electric power does each hydroelectric unit produce?arrow_forwardEnergy that is not utilized for work or heat transfer in the human body is converted to the chemical energy of body fat, which contains about 39 kJ/g. How many grams of fat will you gain if you eat 2450 kcal one day and do nothing but sit relaxed for 16 hours and sleep for the other 8 hours. (Assume sleeping burns 1.2 kcal/min, while sitting relaxed burns 1.7 kcal.min)arrow_forward
- A 60-kg hiker wishes to climb to the summit of Mt. Ogden, an ascent of 5000 vertical feet (1500 m). a.) Assuming that she is 25% efficient at converting chemical energy from food into mechanical work, and that essentially all the mechanical work is used to climb vertically, roughly how many bowls of corn flakes (standard serving size 1 ounce, 100 kilocalories) should the hiker eat before setting out?(b) As the hiker climbs the mountain, three-quarters of the energy from the corn flakes is converted to thermal energy. Ifthere were no way to dissipate this energy, by how many degrees would her body temperature increase?(c) In fact, the extra energy does not warm the hiker's body significantly; instead, it goes (mostly) into evaporating water from her skin. How many liters of water should she drink during the hike to replace the lost fluids? (At 25°C, a reasonable temperature to assume, the latent heat of vaporization of water is 580 cal/g, 8% more than at 100°C.)arrow_forwardYou use a quantity of fuel with a total energy content of 19.02 MJ to power an engine. If the average output of the engine over 2 hours was 2.12 kW, what is the efficiency of the engine?arrow_forwardA sleeping 68 kg man has a metabolic power of 75 W . How many Calories does he burn during an 8.0 hour sleep? Express your answer using two significant figures.arrow_forward
- Many decisions are made on the basis of the payback period: the time it will take through savings to equal the capital cost of an investment. Acceptable payback times depend upon the business or philosophy one has. (For some industries, a payback period is as small as two years.) Suppose you wish to install the extra insulation in Exercise. If energy cost $1.00 per million joules and the insulation was $4.00 per square meter, then calculate the simple payback time. Take the average ΔT for the 120 day heating season to be 15.0ºC.arrow_forwardThe metabolic power for typing is 150 W for Lili, not a lot as you know probably. How long does it take to burn off the energy in a slice of apple pie, which energy content is 1680 kJ (400 food calorie), in minutes? (Try to stay active, working/studying in front of a computer is not the best exercise you can do for your body.) Your answer needs to have 3 significant figures, including the negative sign in your answer if needed. Do not include the positive sign if the answer is positive. No unit is needed in your answer, it is already given in the question statement.arrow_forwardYou push a 33-kg table across a 6.2-m-wide room. In the process, 1.5 kJ of mechanical energy gets converted to internal energy of the table/floor system. What's the coefficient of kinetic friction between the table and floor?arrow_forward
- Similar to the previous problem, we heat about a cup (238 g) of milk (we’ll treat it like water, with a specific heat of 4186 J/kg °C) from refrigerator temperature (3.2 °C) to a comfortable drinking temperature (53.9 °C) in order to make a cup of hot chocolate. First, find the energy required to heat this milk. Next, imagine giving a 1,500 kg truck this same amount of kinetic energy. What speed (in m/s) will the truck be travelling?arrow_forwardA person's basal metabolic rate (BMR) is the rate at which energy is expended while resting in a neutrally temperate environment. A typical BMR is 7.22 x 10° J/day. Convert this BMR to units of watts and kilocalories (or Calories) per hour. HINT (a) watts W (b) kilocalories per hour kcal/h (c) Suppose a 1.00 kg object's gravitation potential energy is increased at a rate equal to this typical BMR. Find the rate of change of the object's height in m/s. (The acceleration of gravity is g = 9.80 m/s2.) m/sarrow_forwardThe total mass of a paratrooper - the person and all the gear - is 118kg. the paratrooper jumps out of an airplane. after the paratrooper opens up his parschute he quickly reaches a constant speed of 3.7m/s. what is the rate at which the potential energy of the paratrooper is converted to the internal energy of the atmosphere?arrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax College
- Glencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-Hill
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