A motor has to perform of work

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

Problem

A motor has to perform

8{,}000\,\text{J}

of work. For the first

10\,\text{s}

it delivers a constant power of

500\,\text{W}

. After that, its power output drops to

300\,\text{W}

and remains constant. How much additional time is required after the first

10\,\text{s}

to finish the work? (a)

6\,\text{s}

(b)

17\,\text{s}

(c)

10\,\text{s}

(d)

15\,\text{s}