- #1

csnsc14320

- 57

- 1

## Homework Statement

A gyroscope consists of a rotating disk with a 48.7cm radius suitably mounted at the midpoint of a 12.2cm long axle so that it can spin and precess freely. Its spin rate is 975 rev/min. The mass of the disk is 1.14kg and the mass of the axle is 130g. Find the time required for one precession if the axle is supported at one end and is horizontal.

## Homework Equations

[tex] \omega_p = \frac{m g r}{L} [/tex]

[tex] \L = I \omega [/tex]

## The Attempt at a Solution

Using the equation, I plugged in (1.14kg+.130kg)(9.8m/s^2)(.112/2m)/(.5(1.14kg)(.487m)^2(32.5pi)) and got that [tex] \omega_p [/tex] = .05 rad/s, which will take 2.074 min to complete one full precession. However, the back of the book says the answer is 1.90 min. Am I forgetting something?