An isolated rail car of mass $M$ is moving along a straight, frictionless track at an initial speed $v_0$. The car is passing under a bridge when $a$ crate filled with $N$ bowling balls, each of mass $m$, is dropped from the bridge into the bed of the rail car. The crate splits open and the bowling balls bounce around inside the rail car, but none of them fall out. Is the momentum of the rail car $+$ bowling balls system conserved in this collision?
Yes, the momentum is completely conserved.
Only the momentum component in the vertical direction is conserved.
Only the momentum component parallel to the track is conserved.
No components are conserved.
A particle of mass m moving with velocity ${V_0}$ strikes a simple pendulum of mass $m$ and sticks to it. The maximum height attained by the pendulum will be
An isolated rail car of mass $M$ is moving along a straight, frictionless track at an initial speed $v_0$. The car is passing under a bridge when $a$ crate filled with $N$ bowling balls, each of mass $m$, is dropped from the bridge into the bed of the rail car. The crate splits open and the bowling balls bounce around inside the rail car, but none of them fall out. What is the average speed of the rail car $+$ bowling balls system some time after the collision?
$Assertion$ : A helicopter must necessarily have two propellers.
$Reason$ : Two propellers are provided in helicopter in order to conserve linear momentum
A rain drop of radius $2\; mm$ falls from a helght of $500 \;m$ above the ground. It falls with decreasing acceleration (due to viscous resistance of the air) until at half its original hetght, it attains its maximum (terminal) speed, and moves with uniform speed thereafter. What is the work done by the gravitational force on the drop in the first and second half of its journey ? What is the work done by the resistive force in the entire journey if its speed on reaching the ground is $10\; m s ^{-1} ?$
A small ball falling vertically downward with constant velocity $4m/s$ strikes elastically $a$ massive inclined cart moving with velocity $4m/s$ horizontally as shown. The velocity of the rebound of the ball is