Question

A particle of mass m moving with horizontal speed 6 $m/sec$.If m<<M then for one dimensional elastic collision, the speed of lighter particle after collision will be ?

• A. 1 m/sec in original direction
• B. 1m/sec opposite to the original direction
• C. 4 m/sec opposite to the original direction
• D. 4 m/sec in original direction

Answer 1

The correct option is A 1 m/sec in original direction

speed of lighter particle = $V1$ m/s

after collision

$V1=\frac{(m1–m2)(m1+m2)}{u}1+\frac{\left(2m2u2\right)}{(m1+m2)}$

here $m1=m,m2=M$

given $m<<M$

hence

$m1=0$

$V1=–u1+\frac{\left(2M\right)}{M}u2$

$V1=–u1+2u2$

$V1=–5+\left(2\right)\left(3\right)$

$V1=1m/s$

lighter particle will move in original direction with speed $1m/s$