Question

A small ball collides with a massive wall, head-
on. If the initial speed of ball is 10 m/s and
coefficient of restitution is 0.2, then the final
speed of ball will be
(1) 4 m/s
(2) 1 m/s
(3) 2 m/s
(4) Zero​

Answer 1

Answer:

2 m/s

Explanation:

1) We know,

Velocity of approach of ball , u = 10 m/s

Coefficient of restitution ,e =  0.2

Velocity of separation , v = ?

Since, Wall is massive , it will be rest for all time.

That is ,

$e=\frac{v_{sep}}{v_{app}}\\ \\=>0.2=\frac{v}{10}\\ \\=>v=2m/s$

Hence, Speed of ball after collision is 2m/s.

Answer 2

Explanation:

It is given that,

Initial speed of the ball, u = 10 m/s

The coefficient of restitution of the ball, e = 0.2

The formula of the coefficient of restitution is given by :

$e=\dfrac{v_2-v_1}{u_1-u_2}$

Where

$u_1\ and\ u_2$ are initial speeds of two bodies and $v_1\ and\ v_2$ are the final speeds of two bodies.

$0.2=\dfrac{v}{10}$

v = 20 m/s

So, the final  speed of ball will be 20 m/s. Hence, this is the required solution.