# angular deccelerartion

Joined Dec 29, 2004
83
Hi,
I need help with the following problem.

A skater does a pirouette at the rate of 2.0 rev / second and then stop within 3/4 rev. Assume that the angular decceleration is constant and calculate its magnitude.

I tried to compute it but I found -18 rad/s[sup]2[/sup].
BUt the textbook gives -17 rad/s[sup]2[/sup].
Please can someone help me with this problem?

Thank you
B

#### m-rice

Joined Nov 25, 2005
2
Originally posted by braddy@Nov 2 2005, 03:12 PM
Hi,
I need help with the following problem.

A skater does a pirouette at the rate of 2.0 rev / second and then stop within 3/4 rev. Assume that the angular decceleration is constant and calculate its magnitude.

I tried to compute it but I found -18 rad/s[sup]2[/sup].
BUt the textbook gives -17 rad/s[sup]2[/sup].
Please can someone help me with this problem?

Thank you
B
[post=11422]Quoted post[/post]​
Use the formula v^2 = u^2 + 2as, where v is final velocity (0), u is initial (2rev/sec) a is acceleration, and s is distance (0.75 rev)

I get a = -16/6 rev/sec^2 = -16.755 rad/sec^2

This is closer to the text book answer!

Martin

PS Did you manage to do the question about the spinning reel?