A crane must do of work to lift a load

PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A crane must do

24\,\text{kJ}

of work to lift a load. It supplies

1\,\text{kW}

of power for the first

15\,\text{s}

, after which the power decreases to

600\,\text{W}

for the rest of the lift. What is the total time taken to complete the task? (a)

24\,\text{s}

(b)

35\,\text{s}

(c)

30\,\text{s}

(d)

25\,\text{s}