An isolated rail car originally moving with speed $v_0$ on a straight, frictionles, level track contains a large amount of sand. $A$ release valve on the bottom of the car malfunctions, and sand begins to pour out straight down relative to the rail car. Is momentum conserved in this process?
The momentum of the rail car alone is conserved
The momentum of the rail car $+$ sand remaining within the car is conserved
The momentum of the rail car $+$ all of the sand, both inside and outside the rail car, is conserved
Both $(A)$ and $(C)$
Particle $A$ of mass $m _{1}$ moving with velocity $(\sqrt{3} \hat{i}+\hat{j})\, ms ^{-1}$ collides with another particle $B$ of mass $m _{2}$ which is at rest initially. Let $\overrightarrow{ V }_{1}$ and $\overrightarrow{ V }_{2}$ be the velocities of particles $A$ and $B$ after collision respectively. If $m _{1}=2\, m _{2}$ and after collision $\overrightarrow{ V }_{1}=(\hat{ i }+\sqrt{3} \hat{ j })\, ms ^{-1},$ the angle between $\overrightarrow{ V }_{1}$ and $\overrightarrow{ V }_{2}$ is$......^o$
A buggy of mass $100\, kg$ is free to move on a frictionless horizontal track. Two men, each of mass $50\, kg$, are standing on the buggy, which is initially stationary. The men jump off the buggy with velocity $=10m/s$ relative to the buggy. In one situation, the men jump one after the other. In another situation, the men jump simultaneously. What is the ratio of the recoil velocities of the buggy in two cases?
A shell of mass $0.020\; kg$ is fired by a gun of mass $100\; kg$. If the muzzle speed of the shell is $80 \;m s^{-1}$, what is the recoil speed in $m/s$ of the gun ?
A wagon weighing $1000\, kg$ is moving with a velocity $50\,km/h$ on smooth horizontal rails. A mass of $250 \,kg$ is dropped into it. The velocity with which it moves now is ......... $km/hour$
Two bodies of mass $4 \mathrm{~g}$ and $25 \mathrm{~g}$ are moving with equal kinetic energies. The ratio of magnitude of their linear momentum is :