Question

A motor car of mass 20 quintal is moving with velocity of 60 km per hour by application of brakes is brought to rest in a distance of 3 kilometre find average force of resistance and newton

Answer 1

Given conditions ⇒

Mass = 20 Quintal = 2000 kg.

Initial Velocity = 60 km/hr.

Distance covered before coming to rest = 3 km.

Final Velocity = 0

Using the Third's Equation of motion,

v² - u² = 2aS

⇒ (0)² - (60)² = 2(a)(3)

⇒ a = -3600/6

∴ a = -600 km/hr²

Now, For the Force,

Force = Mass × Acceleration.

∴ Force = 2000 × -600

= -12 × 10⁵ N.

Negative sign shows that the force is acting in the Opposite direction.

Hope it helps.