Question

A ball of mass 100g is moving with a velocity of 100m per second and is stopped by a man in 0.25s the force applied to stop the ball is

Answer 1

Units are ignored in calculation.

Answer:

Force applied by man is 40 N

Explanation:

 Initial velocity = u = 100ms⁻¹

Here,

  Man stops the ball in 0.25s, it means after 0.25 second velocity of balls becomes 0.

 So, final velocity = v = 0

    Time taken = 0.25 s

We know, v = u + at   { 1st eq. of motion }

⇒ 0 = 100 + a( 0.25 )

⇒ - 100 = a( 0.25 )

⇒ - 100 / 0.25 = a

⇒ - 400 = a

        -ve sign with 400 represents acceleration in opposite direction, which we call retardation.

  In calculation we will take this + ve for man.

Given, mass of ball is 100g = 100/1000 kg = 0.1 kg

  Therefore,

⇒ Force by man = ma

          ⇒ ( 0.1 )( 400 ) N

          ⇒ 40 N