Question

Two putty balls of equal masses moving in mutually perpendicular directions with equal speed, stick together after collision. if the balls were initially moving with a velocity of $45\sqrt{2}m/s$ each, find the velocity of the combined mass after collision.

Answer 1

Since both masses are same and have same speed, the combined mass will move along the bisector of the angles between them since the net momentum along Y-axis is 0.

It is given that initial velocities are perpendicular .

$⟹2\theta ={90}^o⟹\theta ={45}^o$

Applying conservation of momentum along $X-axis$-

$2mv=mu\cos \theta +mu\cos \theta =2mu\cos {45}^o$

$⟹v=\frac{u}{\sqrt{2}}$

$⟹v=45m/s$