A ball of mass 0.1 kg strikes a wall normally with a speed of 30 ms-1 and rebounds with a speed of 20 ms-1 . The impulse of the force exerted by the wall on the ball is

Question

A ball of mass 0.1 kg strikes a wall normally with a speed of 30 ms-1 and rebounds with a speed of 20 ms-1 . The impulse of the force exerted by the wall on the ball is (A)  1 N - s  (B)  5 N - s  (C)  2 N - s  (D)  3 N - s

Tardigrade Admin · Accepted Answer

Impulse = Change is momentum pi-pf direction of pf and pi apposite to each other ∴ Impulse =mu-(-m v) =mu+m v=m(u+v)=0.1(30+20) =0.1 × 50=5 N - s

Q. A ball of mass $0.1 k g$ strikes a wall normally with a speed of $30 m s^{- 1}$ and rebounds with a speed of $20 m s^{- 1}$ . The impulse of the force exerted by the wall on the ball is

$1 N$ - $s$

$5 N$ - $s$

$2 N$ - $s$

$3 N$ - $s$

Impulse = Change is momentum $p_{i} - p_{f}$
direction of $p_{f}$ and $p_{i}$ apposite to each other
$∴$ Impulse $= m u - (- m v)$
$= m u + m v = m (u + v) = 0.1 (30 + 20)$
$= 0.1 \times 50 = 5 N - s$

Q. A ball of mass 0.1kg strikes a wall normally with a speed of 30ms−1 and rebounds with a speed of 20ms−1 . The impulse of the force exerted by the wall on the ball is

1N - s

5N - s

2N - s

3N - s