Question

The Bob of a simple pendulum is pulled to a slide till the string makes an angle 30° to the horizontal and released. While crossing the mean position, velocity of the bob is ( length of the pendulum is 80cm in ms^-1

Answer 1

Explanation:

As bob B is of same material and same mass as the bob A, therefore, on elastic collision, their velocities are exchanged.

Bob A comes to rest and B moves with the velocity of A.

We can prove this by momentum conservation and e=1.

e=

Speedofapproach

Speedofseparation

=

u

1

v

2

−v

1

=1

⇒v

2

−v

1

=u

1

−(I)

mu

1

=mv

1

+mv

2

⇒v

2

+v

1

=u

1

−(II)

Using(I)&(II)

v

1

=0&v

2

=u

1