Question

A rope-way trolley of mass 1200 kg uniformly from rest to a velocity of 72 km/h in 6s. What is the average power of the engine during this period in watt ? (Neglect friction) 

(A) 400 W 

(B) 40,000 W 

(C) 24000 W 

(D) 4000 W

Answer 1

Correct option: (B) 40,000 W

Explanation: 

m = 1200 kg

V = 72 kmph = {(72 × 1000) / (3600)} = 20 m/s

t = 6 sec

power = {(Energy) / (time)}

= [{(1/2)mv²} / 6]

= (1 / 12) × 1200 × 20² 

= 400 × 100

= 40,000 W