A proton of mass $m$ collides elastically with a particle of unknown mass at rest. After the collision, the proton and the unknown particle are seen moving at an angle of $90^o$ with respect to each other. The mass of unknown particle is
$\frac{m}{{\sqrt 3 }}$
$\frac{m}{2}$
$2m$
$m$
Two identical balls $P$ and $Q$ moving in the $x-y$ plane collide at the origin $(x=0,y=0)$ of the coordinate system. Their velocity components just before the moment of impact were, for ball $P$, $v_x=6\ m/s$, $v_y=0$; for ball $Q$, $v_x=-5\ m/s$, $v_y=2\ m/s$. As a result of the collision, the ball $P$ comes to rest. The velocity components of the ball $Q$ just after collision will be
$A$ bal $A$ collides elastically with another identical ball $B$ initially at rest $A$ is moving with velocity of $10m/ s$ at an angle of $60^o$ from the line joining their centres. Select correct alternative :
If a rubber ball falls from a height $h$ and rebounds upto the height of $h / 2$. The percentage loss of total energy of the initial system as well as velocity ball before it strikes the ground, respectively, are :
Two balls $A$ and $B$ having masses $1\, kg$ and $2\, kg$, moving with speeds $21\, m/s$ and $4\, m/s$ respectively in opposite direction, collide head on. After collision Amoves with a speed of $1\, m/s$ in the same direction, then the coefficient of restitution is
A mass $'m'$ moves with a velocity $'v'$ and collides inelastically with another identical mass. After collision the $1^{st}$ mass moves with velocity $\frac{v}{{\sqrt 3 }}$ in a direction perpendicular to the initial direction of motion. Find the speed of the $ 2^{nd}$ mass after collision