A car accelerates uniformly from rest. Ignoring air friction, when does the car require the greatest power? (a) When the car first accelerates from rest, (b) just as the car reaches its maximum speed, (c) when the car reaches half its maximum speed. (d) The question is misleading because the power required is constant. (e) More information is needed.

1) A child pulls on a wagon with a force of 75 N. If the wagon moves a total of 42 m in 3.1 minutes, what is the average power delivered by the child?

Multiple-Concept Example 13 presents useful background for this problem. The cheetah is one of the fastest accelerating animals, for it can go from rest to 31.8 m/s in 3.38 s. If its mass is 119 kg, determine the average power developed by the cheetah during the acceleration phase of its motion. Express your answer in (a) watts and (b) horsepower. (a) Number i (b) Number Units Units

A 699-kg elevator starts from rest and moves upward for 2.60 s with constant acceleration until it reaches its cruising speed, 1.83 m/s. (a) What is the average power of the elevator motor during this period? hp (b) How does this amount of power compare with its power during an upward trip with constant speed? (Give the power during an upward trip with constant speed.) hp Need Help? Read It

A Ford F-150 pickup truck has a mass of 1950 kg.   One truck is equipped with an Ecoboost 2.7 liter V6 engine that produces a useful power output of 242 kW.        (a)  How long in seconds does it take the truck to start from rest and reach a speed of 12.5 m/s, assuming no friction effects and it is traveling on a level road?       (b)  How long will it take to reach the speed of 12.5 m/s from rest, if the truck also climbs a hill that has a height of 2.75 m?

Rank the following bodies in order of their kinetic energy, from least to greatest along with reasons. (i) a 4.0-kg body moving at 10.0 m/s; (ii) a 2.0-kg body that initially was at rest and then had 60 J of work done on it; (iii) a 2.0-kg body that initially was moving at 8.0 m/s and then had 40 J of work done on it; (iv) a 4.0-kg body that initially was moving at 10 m/s and then did 80 J of work on another body.

Suppose a 975-kg car can produce a useful power output of 45.5 hp (1 hp = 746 W).  (a) How long, in seconds, will it take the car to reach a speed of 15.5 m/s, neglecting friction.   (b)  How long, in seconds, will this acceleration take if the car also climbs a 2.9-m high hill in the process?

(a) How long (in s) will it take an 865 kg car with a useful power output of 38.0 hp (1 hp = 746 W) to reach a speed of 13.0 m/s, neglecting friction? (Assume the car starts from rest.) 2.88 X S