일반물리학 1 — Kinetic Energy and Work: Problem 18

18 (a) In 1975 the roof of Montreal’s Velodrome, with a weight of 360 kN, was lifted by 10 cm so that it could be centered. How much work was done on the roof by the forces making the lift? (b) In 1960 a Tampa, Florida, mother reportedly raised one end of a car that had fallen onto her son when a jack failed. If her panic lift effectively raised 4000 N (about $1/4$ of the car’s weight) by 5.0 cm, how much work did her force do on the car?