10.
a) The torque can be written as follow:
where,
I: moment of inertia
α: angular acceleration
τ: torque
Consider that if the angular velocity of the bike wheel is constant, then, the angular acceleration is zero. Then, α and the torque equals zero.
τ = 0 Nm
b) The angular acceleration is given by:
where w is the angular speed. As in the previous point, consider that the angular velocity is constant, then, there is no change in the angular velocity and the angular acceleration is zero.
α = 0 rad/s^2
c) The explanations are given above.