Question

A wheel of moment of inertia of 3.00 kg.m² starts from rest and accelerates under a constant torque of 3.00 N.m for 4.00 s. The wheel's rotational kinetic energy at the end of 4.00 s is =  

A wheel starts at rest, and has an angular acceleration of 4 rad/s². After 4.0 s it will have an angular velocity of  ? rad/s

A wheel starts at rest, and has an angular acceleration of 3.5 rad/s². After 2.0 s it will have an angular velocity of? rad/s

Answer 1

1)
given
I = 3.00 kg.m^2
T = 3.00 N.m
t = 4.00 s
angular acceleration, alfa = T/I

= 3.00/3.00

= 1.00 rad/s^2

wf = wo + alfa*t

= 0 + 1*4

= 4 rad/s

so, final kinetic energy, KEf = (1/2)*I*w^2

= (1/2)*3*4^2

= 24 J   <<<<<<<<<<------------Answer

2) wf = wo + alfa*t

= 0 + 4*4

= 16 rad/s   <<<<<<<<<<------------Answer

3) wf = wo + alfa*t

= 0 + 3.5*2

= 7.0 rad/s <<<<<<<<<<------------Answer