Question

An object of mass 2kg travelling in a straight line with a velocity of 10ms−1 collides with, and sticks to,a stationary wooden block of mass 10kg.Then they both move off together in the same straight line.Calculate the total momentum just before the impact and just after the impact. Also, calculate the velocity of the combined object.

Answer 1

Answer

Given : m

1

=1kg m

2

=5kg u

1

=10 ms

−1

u

2

=0

Momentum of the system just before collision, P

i

=m

1

u

1

+m

2

u

2

P

i

=1×10+5×0=10 kgms

−1

Mass of the combined object, M=m

1

+m

2

=6kg

Let velocity of combined object be v

According to conservation of momentum, momentum of the system just after the collision, P

f

=P

i

⟹P

f

=10 kg m s

−1

Mv=10

or, 6×v=10