Physics
posted by HELP PLZ .
The angular velocity of a process control motor is (21−12t2) rad/s, where t is in seconds.
A)At what time does the motor reverse direction?
I got 6.5s
B) Through what angle does the motor turn between t =0 s and the instant at which it reverses direction?
Can anyone do B

a. 2112t^2=0 or t= sqrt21/12 which is not 6.5 seconds
b. rework a.
displacement=INT (2112t^2) dt from o to T above 
Actually it is 6.5 seconds... I worked it and that's what mastering chemistry said was correct also