1. A spaceship is rotating about its longitudinal axis at 6 rev/min. The occupants wish to stop this rotation. They have small jets mounted tangentially, at a distance R=4m from the axis and can eject 10 g/s if gas from each jet with a nozzle velocity of 800 m/s. For how long must they turn on these jets to stop of the rotation ? The rotational inertia of the ship around its axis (assumed to be constant) is 4000 kg*m^2
2. True or false: If the net torque on a rotating system is zero, the angular velocity of the system cannot change.
The Attempt at a Solution
1. Can anyone suggests me how to this problem ?
2. I know it's false. I try to explain by using dL/dt=0 since net torque is zero. Thus, d (I*w)/dt=0. Thus I* dw/dt + w*dI/dt=0. Since dI/dt= 0, I*dw/dt must be 0 so I can be 0 also, not necessarily dw/dt must be 0. However, my teacher said it's wrong. How do I fix it ??