How High is the Watermelon When Its Kinetic Energy is 4.61J?

[soccerplaya09]

Homework Statement

The largest watermelon ever grown had a mass of 118kg. Suppose this watermelon were exhibited on a platform 5m above the ground. After the exhibition, the watermelon is allowed to slide along to the ground along a smooth ramp. How high above the ground is the watermelon at the moment its kinetic energy is 4.61J.

Homework Equations

Can anyone give me some useful tips to solve problems like these. And how do i solve the problem =).

The Attempt at a Solution

I think i am suposed to use the PEg= mgh but other then that i don't know what i am doing haha.

 

[LowlyPion]

Welcome to PF.

Yes, potential energy is given by m*g*h.

What they are asking for is how much has it dropped to have 4.6 J imparted to its Kinetic energy.

How ever far that is, you subtract from 5 m - the original; height for your answer.