$10\ m$ is the total mass of a cannon that includs all shell. Initial cannon is moving with velocity $10\ m$ is along a horizontal frictionless path. If cannon fires $'n$' shells of mass $m$ in the direction of motion of the cannon one by one with velocity $u$ with respect to ground. (neglect any friction force)
If $u > 10$ after some shots $(n > 1)$ velocity of cannon may become $u$.
If $u < 10$ after some shots $(n > 1)$ velocity of cannon may become $u$.
If $u = 10$ after some shots $(n > 1)$ velocity of cannon may become $u$.
For any speed $v$ and any number of shots cannon speed can not be $u$.
The potential energy of a certain spring when stretched through a distance $S$ is $10 \,joule$. The amount of work (in $joule$) that must be done on this spring to stretch it through an additional distance $S$ will be
Two identical blocks $A$ and $B$, each of mass $'m'$ resting on smooth floor are connected by a light spring of natural length $L$ and spring constant $K$, with the spring at its natural length. $A$ third identical block $'C'$ (mass $m$) moving with a speed $v$ along the line joining $A$ and $B$ collides with $A$. the maximum compression in the spring is
$A$ ball of mass $m$ is attached to the lower end of light vertical spring of force constant $k$. The upper end of the spring is fixed. The ball is released from rest with the spring at its normal (unstretched) length, comes to rest again after descending through a distance $x.$
A spring when stretched by $2 \,mm$ its potential energy becomes $4 \,J$. If it is stretched by $10 \,mm$, its potential energy is equal to
$A$ block of mass $m$ moving with a velocity $v_0$ on a smooth horizontal surface strikes and compresses a spring of stiffness $k$ till mass comes to rest as shown in the figure. This phenomenon is observed by two observers:
$A$: standing on the horizontal surface
$B$: standing on the block
According to observer $B$, the potential energy of the spring increases