일반물리학 1 — Kinetic Energy and Work: Problem 25

25 In Fig. 7-27, 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 \(F_N\)?