average power delivered

A man pushes a lawn mower on a level lawn with a force of 211 N. If 52% of this force is directed forward, and 53 W of power is expended in pushing the mower 7.0 m, how much time is spent in pushing the mower this distance?

A 35.0 kg crate sits on a conveyor belt with s = 0.870. The conveyor belt starts at rest.Once it is turned on, the crate (which follows the belt, so that it stays at rest with respect to thebelt) speeds up to 2.30 m/s in a uniform fashion. How much power does the motor use to turnthe conveyor belt?

A fighter jet is launched from an aircraft carrier with the aid of its own engines and a steam-powered catapult. The thrust of its engines is 2.50 x 105 N. In being launched from rest it moves through a distance of 93.6 m and has a kinetic energy of 4.37 x 107 J at lift-off. What is the work done on the jet by the catapult?

A fighter jet is launched from an aircraft carrier with the aid of its own engines and a steam-powered catapult. The thrust of its engines is 2.37 x 105 N. In being launched from rest it moves through a distance of 80.6 m and has a kinetic energy of 4.56 x 107 J at lift-off. What is the work done on the jet by the catapult?

Measurements in the 1800s showed that a draft horse could provide a maximum steady output power over the course of a working day; that’s how the “horsepower,” about 750 W, came to be defined. Another animal that’s used for pulling loads for which there are good data is the sled dog. A 38 kg dog can provide power to pull a sled with a force of 60 N at a steady 2.2 m/s. Dogs and horses have approximately the same 25% metabolic efficiency as humans. How many sled dogs would be needed to provide 1 horsepower?A. 6               B. 12                  C. 14                 D. 20

In 2.79 minutes, a ski lift raises four skiers at constant speed to a height of 131 m. The average mass of each skier is 70.7 kg. What is the average power provided by the tension in the cable pulling the lift? Number Units

A warehouse worker pushes a 19.1 kg box, increasing its speed from rest to 3.40 m/s. This acceleration occured over a period of 0.933 seconds. How much power did the worker produce?

A 1500 kg sports car accelerates from rest to 95 km/h in 7.0 s What is the average power delivered by the engine? Express your answer using two significant figures.