Question

A body of mass $2kg$ collides with a wall with a speed of $100m{s}^{-1}$ are rebounds with the same speed. If the time of contact is $1/50s$, the force exerted on the wall is

• A. $8N$
• B. $2\times {10}^{4}N$
• C. $4N$
• D. ${10}^{4}N$

Answer 1

The correct option is B $2\times {10}^{4}N$

Force exerted by wall on the body is equal to force exerted by body on wall.
Force exerted on body is equal to the change in momentum divided by the duration of contact.
$\text{Force}=\frac{\text{Change in momentum}\Delta P}{\text{Duration of contact}\Delta t}$

$=\frac{2\times (100-(-100\left)\right)}{\frac{1}{50}}=2\times {10}^{4}N$