If a long spring is stretched by $0.02\, m$,its potential energy is $U$. If the spring is stretched by $0.1\, m$,then its potential energy will be

When a spring is stretched by $10 \ cm$, the potential energy stored is $E$. When the spring is stretched by $10 \ cm$ more, the potential energy stored in the spring becomes (in $E$)

$A$ massless spring of force constant $K$ is placed between two blocks of masses $m$ and $M$ on a frictionless table and compressed by an amount $x$. Upon releasing the spring,both blocks move in opposite directions. The blocks lose contact with the spring when it reaches its natural length. The speed of the block of mass $M$ at the moment of separation is:

If a spring extends by $x$ on loading,then the energy stored by the spring is (if $T$ is tension in the spring and $k$ is spring constant).

The work done in joules in increasing the extension of a spring of stiffness $10\, N/cm$ from $4\, cm$ to $6\, cm$ is:

An engine is attached to a wagon through a shock absorber of length $1.5 \, m$. The system with a total mass of $50,000 \, kg$ is moving with a speed of $36 \, km \, h^{-1}$ when the brakes are applied to bring it to rest. In the process of the system being brought to rest,the spring of the shock absorber gets compressed by $1.0 \, m$. If $90 \%$ of the energy of the wagon is lost due to friction,calculate the spring constant.