How high does the frictionless ramp have to be for the ball....

[mailmas]

Homework Statement

What minimum height does the frictionless ramp have to be for the ball to be able to travel along the ramp into a loop upside down and not fall?
Radius of loop = .3m

Homework Equations

PE + KE = PE + KE

The Attempt at a Solution

mgh_1=mgh_2 + 1/2 mv^2
h_1 = h_2 + v^2/(2g)

h_2 = .3m[/B]
Am I on the right track?

 

[kuruman]

Is there a picture that goes with the question? If there is, please post it.

 

[mailmas]

Is there a picture that goes with the question? If there is, please post it.

No :(

 

[kuruman]

If this is a "loop-the-loop" problem (as I suspect) then your solution is incorrect. If the ball starts at a height equal to the radius, then it can only rise to the same height of 0.3 meters on the other side and slide back. Energy conservation is part of the solution. The other part is that the ball must have enough speed at the top of the loop. How much speed is "enough" must be determined with a free body diagram, which is the remaining part of the solution. Even if you don't have a picture, you need to draw one in order to see what's going on.

 

[mailmas]

If this is a "loop-the-loop" problem (as I suspect) then your solution is incorrect. If the ball starts at a height equal to the radius, then it can only rise to the same height of 0.3 meters on the other side and slide back. Energy conservation is part of the solution. The other part is that the ball must have enough speed at the top of the loop. How much speed is "enough" must be determined with a free body diagram, which is the remaining part of the solution. Even if you don't have a picture, you need to draw one in order to see what's going on.

Would speed be determined by: FN = mv^2/r - mg = 0

 

[haruspex]

Would speed be determined by: FN = mv^2/r - mg = 0

Yes.