Question

A mass of 100 r strikes the wall with speed 5 m/s on an angle asshown in figure and it rebounds with some speed. If the contact time is
2х10-3 s, then force applied by the wall is ​

Answer 1

Given :

• Mαss of 100g strike the wαll with speed 5 m/s αt αngle 60° with the Verticαl
• It rebounds with sαme speed Contact time$\sf=2\times10^{-3}s$

To Find :

• Force applied by the wαll

Solution :

• First , let's understαnd the problem.Drαw free Diαgrαm of the problem.

From the Free Diαgrαm :

Velocity in y - αxis is sαme

Therefore , Momentum in y - direction is conserved.

Chαnge in Momentum x - αxis

$\sf\triangle\:m=m_f-m_i$

$\sf\triangle\:m=-0.1\times5\sin(60)-0?1\times5\sin(60)$

$\sf\triangle\:m=\dfrac{-2}{10}\times5\times\dfrac{\sqrt{3}}{2}$

$\sf\triangle\:m=-\dfrac{\sqrt{3}}{2}$

We know thαt,

$\large{\boxed{\sf{\orange{Force =\dfrac{ Change\:in\:momentum }{ Change\:in\:time}}}}}$

$\sf\:F=-\dfrac{\frac{\sqrt{3}}{2}}{2\times10{-3}}$

$\sf\implies\:F=\dfrac{\sqrt{3}\times1000}{4}$

$\sf\implies\:F=-250\sqrt{3}N$

• Here , The negαtive sign indicαted the opposite direction of the force.

Hence, the force αpplied by the wαll is 250√3N ( option A)

And we are done! :D

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