Question

A mass of $100g$ strikes the wall with speed $5m/s$ at an angle as shown in figure and it rebounds with the same speed. If the contact time is $2\times {10}^{-3}sec$, what is the force applied on the mass by the wall.

• A. $250\sqrt{3}$ to right
• B. $250N$ to right
• C. $250\sqrt{3}$ to left
• D. $250N$ to left

Answer 1

The correct option is C $250\sqrt{3}$ to left

To find the force$,$

Initial momentum$,P_1=mvsin\Theta i+mvcos\Theta j$

Final momentum$,P_2=-mvsin\Theta i+mvcos\Theta j$

Where$,$

$P_1,P_2-$ Initial and final momentum

$m-mass$

$v-speed$

Therefore$,$

Force $=$ Change in momentum $/$ Change in time

$\Delta P/\Delta T$

$-2mvsin\Theta /2\times {10}^{-}3$

Substituting the values$,$

We get$,$

$-2\left(0.1\right)\left(5\right)$ $sin60/2\times {10}^{-}3$

Force $=-250\surd 3N$

The negative sign indicated the opposite direction of the force$.$

Hence, the force applied by the wall is $250\surd 3N$ to left$.$

Hence,

option $\left(C\right)$ is correct answer.