Particle $A$ moving with a velocity $v = 10 \ m/s$ experiences a head-on collision with a stationary particle $B$ of the same mass. As a result of the collision,the kinetic energy of the system decreases by $1 \%$. The speed of particle $A$ after the collision is: (in $m/s$)

Ball $1$ collides with another identical ball at rest. For what value of coefficient of restitution $e,$ the velocity of the second ball becomes two times that of the first ball after the collision?

$A$ ball is dropped from a height $h$. As it bounces off the floor,its speed is $80$ percent of what it was just before it hit the floor. The ball will then rise to a height of most nearly .............. $h$.

$A$ sphere collides with another sphere of identical mass. After collision,the two spheres move. The collision is inelastic. Then the angle between the directions of the two spheres is

Two pendulums with identical bobs and lengths are suspended from a common support such that in rest position the two bobs are in contact (figure). One of the bobs is released after being displaced by $10^{\circ}$ so that it collides elastically head-on with the other bob.
$(a)$ Describe the motion of two bobs.
$(b)$ Draw a graph showing variation in energy of either pendulum with time,for $0 \leqslant t \leqslant 2T$,where $T$ is the period of each pendulum.

$A$ sphere of mass $m$ moving with velocity $u$ undergoes a collision with a stationary sphere of mass $m$. If the coefficient of restitution is $e = 1/2$,what is the ratio of the final velocities of the two spheres?