Solve Simple Loop Problem: Find Speed at Point A

[Guruu]

Homework Statement

A bead slides without friction around a loop-the-loop as shown in the figure below. The bead is released from a height h = 3.75R.

(a) What is the bead's speed (V) at point A? Answer in terms of R and g, the acceleration of gravity.

I don't have the picture it's in the book so I'll describe it. It's a downward slope that go's into a loop. 'A' is at the the top of the loop and R is the loop's radius.

Homework Equations

a=v^2/r

The Attempt at a Solution

Since it's perfectly parallel with the y axis, and therefor i assume a is 9.81, I get (gr)^1/2, but my webassignment program says that's wrong.

 

[tiny-tim]

A bead slides without friction around a loop-the-loop as shown in the figure below. The bead is released from a height h = 3.75R.
…
(a) What is the bead's speed (V) at point A? Answer in terms of R and g, the acceleration of gravity.
…
a=v^2/r
…
Since it's perfectly parallel with the y axis, and therefor i assume a is 9.81, I get (gr)^1/2, but my webassignment program says that's wrong.

Hi Guruu!

What does a=v^2/r have to do with part (a)?

Hint: use conservation of energy.

 

[arpanroy]

yup conservation of energy is the way to go