A ball of mass $10\, kg$ moving with a velocity $10 \sqrt{3} m / s$ along the $x-$axis, hits another ball of mass $20\, kg$ which is at rest. After the collision, first ball comes to rest while the second ball disintegrates into two equal pieces. One piece starts moving along $y-$axis with a speed of $10$ $m / s$. The second piece starts moving at an angle of $30^{\circ}$ with respect to the $x-$axis. The velocity of the ball moving at $30^{\circ}$ with $x-$ axis is $x\, m / s$. The configuration of pieces after collision is shown in the figure below. The value of $x$ to the nearest integer is
$15$
$24$
$20$
$30$
A particle of mass $m$ moving horizontally with $v_0$ strikes $a$ smooth wedge of mass $M$, as shown in figure. After collision, the ball starts moving up the inclined face of the wedge and rises to $a$ height $h$. The maximum height h attained by the particle is
A light spring of length $20\, cm$ and force constant $2\, kg/cm$ is placed vertically on a table. A small block of mass $1\, kg$. falls on it. The length $h$ from the surface of the table at which the ball will have the maximum velocity is ............... $\mathrm{cm}$
A neutron moving with a speed $'v'$ makes a head on collision with a stationary hydrogen atom in ground state . The minimum kinetic energy of the neutron for which inelastic collision will take place is....$eV$
From a stationary tank of mass $125000$ pound a small shell of mass $25$ pound is fired with a muzzle velocity of $1000\, ft/sec$. The tank recoils with a velocity of ............ $\mathrm{ft/sec}$
A spaceship of speed $v_0$ travelling along $+ y$ axis suddenly shots out one fourth of its part with speed $2v_0$ along $+ x$ -axis. $xy$ axes are fixed with respect to ground. The velocity of the remaining part is