Question

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

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, $m=150g=150\times 10^{-3}kg,a=20m/s^2$
$\therefore F=0.15\times 20=3N$
Impulse $=F\Delta t=3\times 0.1=0.3N-s$
Note: Impulse is a vector quantity, its direction is the same as that of the force.