- #1

crybllrd

- 120

- 0

## Homework Statement

A string exerts a tension force of 55N on a 10kg block as it moves a distance of 5m up a frictionless incline. The string pulls parallel to the incline.

A) Find the total external work done on the block-earth system as the block moves 5m up the incline.

B)Find the change in gravitational potential energy for the block-earth system as the block moves 5m up the incline.

C)Find the change in kinetic energy for the block-earth system as the block moves 5m up the incline.

## Homework Equations

[tex]KE=\frac{1}{2}mv^{2}[/tex]

[tex]PE_{g}=mgh[/tex]

Our teacher tells us to round gravity up to 10m/s/s.

## The Attempt at a Solution

A)The external force should be the tension, so:

[tex](55N)(5m) = 275J[/tex]

B)I used trig (3-4-5 triangle) to find the height to go up 3m.

[tex]mgh_{f}-mgh_{i}=\Delta KE[/tex]

[tex](10)(10)(3)-(10)(10)(0)=300J[/tex]

C)[tex]KE_{f}-KE_{i}=\DeltaKE[/tex]

I am not sure what to do here because I don't know how to solve for velocity.