Question

An object of mass `1kg` travelling in a straight line with a velocity of `10m//s` collides with, and sticks to, a stationary wooden block of mass `5kg`. 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

Here, `m_(1) = 1kg, u_(1)= 10m//s , m_(2) 5kg u_(2) = 0`
Before impact, total momentum `= m_(1)u_(1)+m_(2)u_(2)`
or `P_(1) = 1xx10+5xx0 = 10kg m//s`
just after impact, total momentum remains the same, i.e.,
`P_(2)=P_(1)=10 kg m//s`
If v is velocity of the combined object,
then from `P_(2)= (m_(1)+m_(2))v, v=p_(2)/(m_(1)+m_(2))= 10/((1+5))= 1.67 m//s`