Question

A ball falls from $20m$ height on floor and rebounds to $5m$. Time of contact is $0.02s$. Find acceleration during impact.

• A. $1200m/s^2$
• B. $1000m/s^2$
• C. $2000m/s^2$
• D. $1500m/s^2$

Answer 1

Answer: (D)

According to Newtons second law of motion force acting on a body is equal to the rate of change of momentum during impact.
$F=\frac{\Delta p}{\Delta t}$
Also, $F=ma$
$\therefore$ $ma=\frac{p_2-p_1}{\Delta t}$
Or $a=\frac{m{v}_2-(-m{v}_1)}{m\Delta t}$
Or $a=\frac{v_2+v_1}{\Delta t}$
$\therefore$ $a=\frac{\sqrt{2\times 10\times 20}+\sqrt{2\times 10\times 2}}{0.02}$
Or $a=\frac{20+10}{0.02}$
$=1500m/s^2$