Question

Two girls of equal mass m jump off the border line of a stationary carriage of mass M with same horizontal velocity u relative to the carriage. Nelgecting the effect of friction :

• A. they will impact greater velocity to the carriage by jumping of simultaneously.
• B. they will impact greater velocity to the carriage by jumping one after the other.
• C. they will impact greater velocity to the carriage in whatever manner they jump off.
• D. insufficient data to reply.

Answer 1

The correct option is B they will impact greater velocity to the carriage by jumping one after the other.

When girls jump one by one total velocity of the system will be more because from conservation of momentum, velocity of car in this case will be

$u_{car}=u(\frac{1}{M+2m}+\frac{1}{M+m})$

instead of $u(\frac{1}{M+2m}+\frac{1}{M+2m})$ when they jump simultaneously.