Two students were given a physics problem for finding maximum extension of spring if blocks are imparted velocities `v_(1)` & `V_(2)` when spring is unstrected.
By Students A: `1/2m(v_(1)+v_(2))^(2)=1/2kx^(2)`
By Students B: `1/2mv_(1)^(2)+1/2mv_(2)^(2)=1/2kx^(2)`

Options

A. Student A is correct, Student B is wrong
B. Student B is correct, Student A is wrong
C. both are correct
D. both are wrong

Answer

D

Explanation

Velocity of centre of mass is non zero
`1/2(m/2)(v_(1)+v_(2))^(2)=1/2kx^(2)max`