An object of mass 1 kg travelling in a straight line with a velocity of 10 m s^–1 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.

Given

m_1​=1kg               m₂​=5kg         

u₁​=10 ms⁻¹          u₂​=0 ms⁻¹

Momentum of the system just before collision, 

P_i  ​=m₁ ​u_{1 ​}+ m₂​ u_2​

P_i ​= 1×10 + 5×0 = 10 kgms⁻¹

Mass of the combined object, M=m₁​+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​

Hence, P_f​ =10 kg m s⁻¹

M x v = 10 kg m s⁻¹  

v=1.67 m/s

Hence  the velocity of the combined object is 1.67 m/s