- #1

Mr Davis 97

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- 44

## Homework Statement

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A mover pushes a 700 kg piano from rest up a ramp with a 9° slope. The piano is traveling at 2 m/s when it is 3 m above the ground. How much force does the mover exert on the piano?

## Homework Equations

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##W = \Delta K##

## The Attempt at a Solution

I started with the equation ##F_{net}d\cos\theta = \frac{1}{2}mv^{2}##Then I solved for the net force: ##F_{net} = \displaystyle\frac{mv^{2}}{2d\cos\theta}##I then solved for displacement: ##d = \displaystyle\frac{3}{\sin9^{\circ}} = 19.2##Next, I found the net force: ##F_{net} = 73~N##This is the net force on the body, so I found the force that the mover exerted against gravity to find what he exerted, which came out to me ##1150~N##. However, this is this the incorrect answer. My textbook says that the correct answer is 73 N. But isn't this the net force on the body, and not the force that the mover exerts? Please explain what I am doing wrong.