AP EAPCET 04-Jul-2022 Shift 2 Paper

According to first situation
Total momentum before collision,
pi‌=mvA+2mvB
‌=m×150+2m×v=150m+2mv
Since, coefficient of restitution, e=1
Hence, after collision, body A transfer its complete velocity to body B. hence, after collision velocity of body B,v′=150−v.
Total momentum after collision,
pf‌=2mv′+m×0
‌=2mv′
‌=2m(150−v)
According to law of conservation of momentum,
pi‌=pf
150m+2mv‌=2m(150−v)
150+2v‌=300−2v⇒4v=150
⇒‌‌v‌=37.5m∕ s