question_answer

A 6 kg mass collides with a body at rest. After collision, they travel together with a velocity equal to one-third of the velocity of 6 kg mass. Find the mass of the second body.

Answer:

\[{{m}_{1}}=6kg,\,\,{{m}_{2}}=?\] \[{{u}_{1}}=u,\,\,{{u}_{2}}=0\] Let 6 kg mass velocity be ?u?. \[\therefore v=\frac{1}{3}\]of \[u=\frac{u}{3}\] According to the law of conservation of momentum, \[\Rightarrow 6\times u+{{m}_{2}}\times 0=({{m}_{1}}+{{m}_{2}})\frac{u}{3}\] \[\Rightarrow 6u=(6+{{m}_{2}})\frac{u}{3}\Rightarrow {{m}_{2}}=12kg\]