Halliday, Resnick & Walker — Kinetic Energy and Work: Problem 25

In Fig. 7.19, a 0.250 kg block of cheese lies on the floor of a 900 kg elevator cab that is being pulled upward by a cable through distance \( d_1 = 2.40 \text{ m} \) and then through distance \( d_2 = 10.5 \text{ m} \). (a) Through \( d_1 \), if the normal force on the block from the floor has constant magnitude \( F_N = 3.00 \text{ N} \), how much work is done on the cab by the force from the cable? (b) Through \( d_2 \), if the work done on the cab by the (constant) force from the cable is \( 92.61 \text{ kJ} \), what is the magnitude of \( F_N \)?