**28. As the engine in a car forces its wheels to turn, static friction between the road and the wheels of a car produces a force of 1000 N acting forward on the car to keep it going at a constant speed of 25 m/s. a) How much work does the static friction force do to the car as the car travels along the road for 10 seconds? b) At what rate in watts is the power being supplied? c) A horsepower is a U.S. unit of power, equal to 746 watts. Convert the power from part (b) into horsepower

**28. As the engine in a car forces its wheels to turn, static friction between the road and the wheels of a car produces a force of 1000 N acting forward on the car to keep it going at a constant speed of 25 m/s. a) How much work does the static friction force do to the car as the car travels along the road for 10 seconds? b) At what rate in watts is the power being supplied? c) A horsepower is a U.S. unit of power, equal to 746 watts. Convert the power from part (b) into horsepower

College Physics

1st Edition

ISBN:9781938168000

Author:Paul Peter Urone, Roger Hinrichs

Publisher:Paul Peter Urone, Roger Hinrichs

Chapter7: Work, Energy, And Energy Resources

Section: Chapter Questions

Problem 8PE: Suppose the ski patrol lowers a rescue sled and victim, having a total mass of 90.0 kg, down a 60.0°...

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A student expends 7.5 W of power in lifting a textbook 0.50 m in 1.0 s with a constant velocity. (a) How much work is done, and (b) how much does the book weigh (in newtons)? The answers to Confidence Exercises may be found at the back of the book.
Give an example of a situation in which there is a force and a displacement, but the force does no work. Explain why it does no work.
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a shopper in a supermarket pushes a cart with a force of 35 N directed at an angle of 25 below the horizontal. The force is just sufficient to overcome various frictional forces, so the cart moves at constant speed, (a) Find the work done by the shopper as she moves down a 50.0-m length aisle, (b) What is the net work done on the cart? Why? (c) The shopper goes down the next aisle, pushing horizontally and maintaining the same speed as before. If the work done by frictional forces doesnt change, would the shoppers applied force be larger, smaller, or the same? What about the work done on the cart by the shopper?
a shopper in a supermarket pushes a cart with a force of 35 N directed at an angle of 25 below the horizontal. The force is just sufficient to overcome various frictional forces, so the cart moves at constant speed, (a) Find the work done by the shopper as she moves down a 50.0-m length aisle, (b) What is the net work done on the cart? Why? (c) The shopper goes down the next aisle, pushing horizontally and maintaining the same speed as before. If the work done by frictional forces doesnt change, would the shoppers applied force be larger, smaller, or the same? What about the work done on the cart by the shopper?
A boy starts at rest and slides down a frictionless slide as in Figure P5.64. The bottom of the track is a height h above the ground. The boy then leaves the track horizontally, striking the ground a distance d as shown. Using energy methods, determine the initial height H of the boy in terms of h and d. Figure P5.64
A worker pushes a wheelbarrow with a horizontal force of 50 N on level ground over a distance of 5.0 m. 11 a friction force of 43 N acts on the wheelbarrow in a direction opposite that of the worker, what work is done on the wheelbarrow by the worker? (a) 250 J (b) 215 (c) 35 J (d) 10 J (e) None of those answers is correct.
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Integrated Concepts (a) Calculate the force the woman in Figure 7.46 exerts to do a push-up at constant speed, taking all data to be known to three digits. (b) How much work does she do if her center of mass rises 0.240 m? (c) What is her useful power output if she does 25 push-ups in 1 min? (Should work done lowering her body be included? See the discussion of useful work in Work, Energy, and Power in Humans. Figure 7.46 Forces involved in doing push-ups. The woman's weight acts as a force exerted downward on her center of gravity (CG).
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