Homework Help: How do I find the height at which a ball is released in a friction-les loop question?

1. Feb 7, 2012

True__Fiction

At the top of a "frictionless" loop that is 75 cm high, a 75 Kg ball bearing is travelling at 1.9m/s. From what height was the ball released?

I have absolutely no Idea where to start here.

Diameter= 0.075m
Velocity=1.9m/s
Force related to Gravity=0.74N
m=0.075Kg

2. Feb 7, 2012

Brunetto

Re: How do I find the height at which a ball is released in a friction-les loop quest

If you are using energy like your tag suggests then write out your energy equation:

ΔE = ΔKv + ΔKr + ΔEtherm + ΔUpot

Etherm can be neglected because the loop is frictionless. Substitute in your energy equations for your change in kinetic energy (HINT ball is assumed to start from rest unless the question otherwise states), the change in kinetic rotational energy (HINT that of a point mass) and your change in potential energy (which will have an unknown value). Solve for unknown and you should get your answer...

3. Feb 7, 2012

True__Fiction

Re: How do I find the height at which a ball is released in a friction-les loop quest

That makes much more sense, THANK YOU

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