Question

A 2-ton vehicle travels at 20m/s on a road where the frictional force is 10% of the weight of the vehicle. What is the power required? (Assume g = 10m/s^2)

(a) 220 kW

(b) 240 kW

(c) 420 kW

(d) 440 kW

I have been asked this question in my homework.

Query is from Power topic in portion Work, Energy and Power of Physics – Class 11

Answer 1

Right option is (d) 440 kW

Easiest explanation: Weight of car = m x g

 = 2,000 x 10

 = 20,000 N

Frictional force = (10/100) x (20,000)

 = 2,000 N

Total force (F) = 20,000 + 2,000

 = 22,000 N

Velocity (v) = 20 m/s

P = F x v

 = 22,000 x 20

 = 4,40,000 W

 = 440 kW.