Finding the Velocity of a Frictionless Roller Coaster at the Top of a Loop

[Shahni]

The question is "A roller coaster at a popular amusement park has a portion of the track that is similar to the diagram provided. Assuming that the roller coaster is friction less, find its velocity at the top of the loop.

Homework Statement

Vi = 0 m/s
Vf = ?
Distance from bottom to the very top is 70m
Distance from bottom to the loop is 30m

Homework Equations

Ek = 1/2m x v^2?
Eg = m x g x Delta h?

The Attempt at a Solution

What do I have to find first in order to find the velocity?

 

[PhanthomJay]

Since there is no friction, mechanical energy is conserved. Whatever energy the coaster has at the start, it must have that same energy at the top of the loop. Try the conservation of energy principle and please show your work.

 

[e.bar.goum]

I obviously don't know what the track on the diagram looks like, but it looks like you should consider energy conservation in this instance.

 

[JHamm]

Since it begins at rest the kinetic energy at the top of the loop will be the change in potential energy.

 

[netgypsy]

I'm assuming the coaster is at rest at the top of the 70 meter loop so the drive motor will provide just enough mechanical energy to get the coaster to the very top, then it will be released from there to continue to the loop so ask yourself what its doing at the loop before you write any equations. You are being told that no energy is lost in the trip from the top to the loop.