Ncert Exercises & Solutions

Q. 24 A woman throws an object of mass 500 g with a speed of 25 m/s.
(a) What is the impulse imparted to the object?
(b) If the object hits a wall and rebounds with half the original speed,
what is the change in momentum of the object?

Hint: Impulse = Change in momentum.

Step 1: Find impulse in the first part

Mass of the object (m) = 500g = 05 kg
Speed of the object (v) 25 my's

(a) Impulse imparted to the object = change in momentum

$\begin{array}{l} = m v - m u \\ = m (v - u) \\ = 0.5 (25 - 0) = 12.5 N - s \end{array}$

Step 2: Find the change in momentum in the second part

(b) Velocity of the object after rebounding

$\begin{array}{l} = - \frac{25}{2} m / s \\ v^{'} = - 12 .5 m / s \\ ∴ Change in momentum = m (v^{'} - v) \\ = 0 .5 (- 12 .5 - 25) = - 18 .75 N - s \end{array}$