Question

A block of mass 2m moving with constant velocity 3v collides with another block of mass m at rest and stick to it. Find velocity of the compound block

Answer 1

Let the final velocity be V, by which the combined system of masses move after collision.

Since no external force is assumed t act on the system, the linear momentum is conserved, i.e.,

$\displaystyle\longrightarrow\sf{2m(3v)+m(0)=(2m+m)V}$

$\displaystyle\longrightarrow\sf{6mv=3mV}$

$\displaystyle\longrightarrow\sf{\underline{\underline{V=2v}}}$

Answer 2

Answer: Applying the Momentum Conservation law.

[2m*3v] + [m*0] = 3m*u

=> u = 2v

Note: Here u is the final velocity of compound mass.