Question

(a) The roof of a large arena, with a weight of 410 kN, is lifted by 34 cm so that it can be centered. How much work is 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 cm, how much work did her force do on the car?

Answer 1

a) W = 139.4 kJ

b) W = 200J

Step-by-step explanation:

a) given;

Force F = 410kN

distance d = 34cm = 0.34m

Workdone = force × distance = Fd

Substituting the values;

Workdone = 410kN × 0.34m = 139.4 kJ

b) given;

Force F = 4000N

distance d = 5cm = 0.05m

Workdone = force × distance = Fd

Substituting the values;

Workdone = 4000N × 0.05m = 200J