power mower does 8 x 104 J of work in 0.4 h. What power does it use

44. A metal ramp 6.00 m long is tilted 10.0° and is used to load and unload a moving van. Suppose a 20.0 kg box is pushed up the ramp and it slides with a friction coefficient of 0.30. The ramp can be viewed as a "machine" where the useful output is the potential energy gain of the box and the input is the physical work done by the person doing the pushing. (a) Determine the efficiency of the ramp. (b) Determine the ratio of the force needed to lift the box without the ramp to the force needed to push it along the ramp (this is called the mechanical advantage).

A 1500kg car is travelling with an initial velocity of 30.0 km/h while traveling through a school zone. Upon exiting the school zone the car accelerates to reach a speed of 65.0 km/h in 6.60 s. If the engine supplied 45.0 kW of power to do this, what is the efficiency of the engine?

4. An engine that worked for 46 s consumed E = 23,500 J and lifted a in 75 kg body from the ground to a height of 21 m above the ground.

1. A box with a mass of 3.0 kg is accelerated from rest by a constant force across a floor at a rate of 1.7 m/s for 6.5 s. (a) How much work does the force do on the box? (b) How much power is produced by the force in moving the box?

Number 6

1a. A student does 125.0 J of work lifting a 12.0 kg book. How high was the book lifted? 1b.The book from problem 1 is then allowed to slide down a straight ramp which makesa 26.0o angle above the horizontal, and the book reaches its original position at the endof this ramp. How fast would it be going if there was no friction?

44. A metal ramp 6.00 m long is tilted 10.0° and is used to load and unload a moving van. Suppose a 20.0 kg box is pushed up the ramp and it slides with a friction coefficient of 0.30. The ramp can be viewed as a “machine” where the useful output is the potential energy gain of the box and the input is the physical work done by the person doing the pushing. (a) Determine the efficiency of the ramp. (b) Determine the ratio of the force needed to lift the box without the ramp to the force needed to push it along the ramp (this is called the mechanical advantage).

An elevator engine lifts a total load of 3,659 N weight with constant speed of 2.8 m/s. What is the power consumption of the elevator? Express your answer in watts. plz help and use g = 9.8

4. A car crashes into a tree. What is the work done by the tree stopping the car? The car has a mass of 2075 kg and was traveling at 20.45 m/s. Include a negative if appropriate. Previous submissions: