Question

A car's wheel has a rotational inertia of 3.1 kg m². Working in a coordinate system where counterclockwise is positive, answer the following questions. Treat parts a, b, and c as stand-alone questions; the response from one is not needed for the following parts.

a) If the wheel is spinning with an angular velocity of 6 rad/s counterclockwise and then a torque of 15 N m is applied over a time interval of 4 s, What is the wheel's final angular momentum?
__ kg m² /s

b) The wheel begins from rest, starting to rotate when a torque of 4 N m is applied. Its final angular velocity is 12 rad/s. How long was the torque applied to the wheel?
__s

c) After a constant torque is applied to the wheel for 12 s, its angular speed changes from 6 rad/s clockwise to 6 rad/s counterclockwise. What was the torque applied to the wheel?
__ N m

Answer 1

Angular acceleration, where is torque and I is moment of inertia.

a)

Using

  

Final angular momentum, L =

b)   
   Using,   

On solving,

c)

Torque,