Question

A car of mass 1000 kg accelerates uniformly from rest to a velocity of 54 km/hour in 5s. The average power of the engine during this period in watts is (neglect friction)

• A. 2000 W
• B. 22500 W
• C. 5000 W
• D. 2250 W

Answer 1

Answer: (B)

22500 W

Answer 2

Power$= \frac { \text { Work done } } { \text { time } } = \frac { \text { Increase in K.E. } } { \text { time } }$

$P = \frac { \frac { 1 } { 2 } m v ^ { 2 } } { t } = \frac { \frac { 1 } { 2 } \times 10 ^ { 3 } \times ( 15 ) ^ { 2 } } { 5 } = 22500 \mathrm {~W}$