Question

A ball of mass $150\,g$ moving with an acceleration $20 \,m/s^2$ is hit by a force, which acts on it for $0.1\, s$. The impulsive force is :

• A. 0.5 N-s
• B. 0.1 N-s
• C. 0.3 N-s
• D. 1.2 N-s

Answer 1

Answer: (C)

0.3 N-s

Answer 2

If a constant force $\vec{F}$ is applied a body for a short interval of time $\Delta t,$
then the impulse of this force will be $\vec{F} \times \Delta t$
Also from Newton's law $\vec{F}=m \vec{a}$
Where $m$ is mass and a is acceleration.
Given, $m=150 \,g=150 \times 10^{-3} \,kg , a=20\, m / s ^{2}$
$\therefore F=0.15 \times 20=3 \,N$
Impulse $=F \Delta t=3 \times 0.1=0.3\, N-s$
Note: Impulse is a vector quantity, its direction is the same as that of the force.