NTA Abhyas JEE Main2020PhysicsWork, Power and EnergyPractice
An engine of power 58.8 kW pulls a train of mass 2 × 10 5 kg with a velocity of 36 km h - 1 . The coefficient of static friction is
Options
- A0.3
- B0.03
- C0.003
- D0.0003
Correct answer
C. 0.003
Step-by-step solution
Power of engine, P = 58.8 kW = 58.8 × 10 3 W Mass of the train, m = 2 × 10 5 kg Velocity of train, v = 36 km h - 1 = 36 × 10 3 60 × 60 = 10 m s - 1 Power, P = F ⋅ v ∴ F = P v = 58.8 × 10 3 10 = 5880 N Let the coefficient of friction is μ ∴ F = f s = μ m g ⇒ μ = F m g = 5880 2 × 10 5 × 10 = 0.003