Question

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

By law of conservation of linear momentum, the total momentum before impact is the same as that after the impact. Thus,

$(1\times 10)+(5\times 0)=(1+5)v\\\\\\10=6v\\\\\\v=\dfrac {5}{3}\ m\ s^{-1}$

Thus the velocity of the combined system is $\dfrac {5}{3}\ m\ s^{-1}$ and the total momentum is $10\ kg\ m\ s^{-1}.$