**(a)**The angular momentum is the product of the moment of inertia and the angular velocity. The moment of inertia of a uniform cylinder is given by

I = (m/12)(3r^2 + h^2) = (55 kg/12)(3(.15 m)^2 + (1.5 m)^2) = 10.6219 kg m^2

So the angular momentum is

Iω = (10.6219 kg m^2)(3.5*2π)/s =

**233.587 kg•m^2/s**

**(b)**To stop her in 5 seconds, the needed torque is

T = Iω/t = (233.587 kg m^2/s)/(5 s) =

**46.7174 N•m**

A newton (N) has units of kg•m/s^2, so a newton-meter has units of kg•m^2/s^2.