Question

Two equal masses m1 and m2 moving along same straight line with velocities +3m/s and –5m/s respectively collide elastically. Their velocities after collision will respectively

Answer 1

We know that in an elastic collision,

m1u1 + m2u2 = m1v1 + m2v2.

The masses are equal, so m1=m2 = m.

After the collision, the two masses will stick together, so they will move with a common velocity that we take as v.

Now, Substituting the values in formula, we have -

m3 + m(-5) = (m + m)v

-2m = 2mv

-2m/2m = -1 m/s = v.