What Time Does the Wheel Come to a Stop?

[bluejade]

At t=0 at grinding wheel has an angular velocity of 24.0 rad/s. It has a constant angular acceleration of 30.0 rad/ s2 until circuit breaker trips at t=2.00s. From then on, it turns through 432 rad as ut coasts to a stop at constant angular acceleration. a) through what total angle did the wheel turn between t=0 and the time it stopped? b) when did it stop? c) what was its acceleration as it slowed down?


I tried the problem but I am doubting my answers. for a) i got a really big answer :S
b)12 sec
c)-8.2 rad/s2

Can someone help me solve these problems please?

 

[LowlyPion]

At t=0 at grinding wheel has an angular velocity of 24.0 rad/s. It has a constant angular acceleration of 30.0 rad/ s2 until circuit breaker trips at t=2.00s. From then on, it turns through 432 rad as ut coasts to a stop at constant angular acceleration. a) through what total angle did the wheel turn between t=0 and the time it stopped? b) when did it stop? c) what was its acceleration as it slowed down?

I tried the problem but I am doubting my answers. for a) i got a really big answer :S
b)12.2 sec
c)-8.2 rad/s2

Can someone help me solve these problems please?

What formula did you use to solve for the peak angular velocity?

Without the peak angular velocity, how is it that you could determine the deceleration and the time?

 

[arunma]

I haven't worked it out on paper yet, but from the looks of it this problem seems to require you to use the rotational versions of the kinematic equations of motion. Earlier in your physics class you likely learned about the four equations of motion that can be used to solve kinematics problems. If you turn the distances into angles, the velocities into angular velocities, and the accelerations into angular accelerations, you'll get four equations of motion for rotational kinematics. That should help you to solve the problem.