hey guys,

i couldn't figure out this question. Can anyone help me do this question.

 

- 2 persons are skiing down the frictionless hill. The height of the hill is 12m. Calculate the velocity (m/s) at the end of the hill (assume the initial velocity is 0m/s)

 

- I think it has something to do with Kinetic Energy. But, i don't know where to start from. I need the answer for Monday. So, if anyone can solve this problem, I would be thankful.

I don't think you can solve that without some more information (the slope of the hill).

maybe mass would help. Let's assume that the mass of the person is 50 kg. But, our teacher didn't even give us the mass to solve the problem.

You really need to have the angle to solve this problem.

Rudani,

 

You can solve this using the concept of kinetic energy.

 

Remember change in KE = the change in potential energy.

 

You do not need to have the angle since potential energy is a non-conservative force (I think).

 

The change in potential energy would simply be

9.8m/s^2 X mass X (the change in height).

 

By the time the skier gets to the bottom of the hill, the magnitude of the potential energy that I have shown above will be converted to kinetic energy.

 

So since the change in KE will be equal to KE (final) - KE (initial)

and since the initial KE is zero, since velocity is zero we can say that

 

9.8m/s^2 X mass X (the change in height) = X (velocity squared)

 

You see that mass is on both sides, you can cancel them out

 

9.8m/s^2 X (the change in height) = (velocity squared)

 

Solve for velocity

 

You need anymore help with any other hw problems go to

http://www.physicsforums.com and go to homework help section.

Thank you very much Meninger.

I got the idea of how to solve the problem.