Question

two spheres travel along the same line with velocities u1 and u2. They collide and after collision
their velocities are v1 and v2.
before collision u1
after collision v1
before collision u2
after collision v2
Which collision is not elastic?
u1 / m s–1 u2 / m s–1 v1 / m s–1 v2 / m s–1
A 2 –5 –5 –2
B 3 –3 0 6
C 3 –2 1 6
D 5 2 3 6

Answer 1

only option (1) is correct because e=3/7 which is less than 1 .

so it is not elastic collision..