How do you calculate the average angular acceleration of a spinning wheel?

[tnutty]

Homework Statement

A wheel is spinning at 43rpm with its spin axis vertical. After 15s , it's spinning at 62rpm with its axis horizontal. Find (a) the magnitude of its average angular acceleration.

ans:______rad/s/s

Homework Equations

$$\alpha$$ = $$\varpi$$ /t

attempt :

change in omega is 2pi/60 (62-43)
t = 15
so divide them to get rad/s/s
=
1.3 * 10^-1

 

[rl.bhat]

First of all find the angular momentum L.
Then find the rate of change of angular momentum.
Note that L is a vector.So when you find change in L, you have to use vector subtraction. Finally equate it to I*alpha.

 

[nlightner]

rad/s/s

This is the correct approach to finding the average angular acceleration of a spinning wheel. The formula used, \alpha = \varpi /t, is the correct formula for calculating angular acceleration. The change in angular velocity, \varpi, is calculated by taking the difference between the final and initial angular velocities, which is 2pi/60 (62-43) in this case. The time, t, is given as 15 seconds. Dividing these values gives the average angular acceleration in units of rad/s/s. The calculated value of 1.3 * 10^-1 rad/s/s is the magnitude of the average angular acceleration of the spinning wheel.