A pulley fixed to the ceiling of an elevator car carries a thread whose ends are attached to the loads of masses `m_1` and `m_2`. The car starts going up with an acceleration `w_o`. Assuming the masses of the pulley and the thread, as well as the friction, to be negligible find:
(a) the acceleration of the load `m_1` relative to the elevator shaft and relative to the car,
(b) the force exerted by the pulley on the ceiling of the car.