A body of mass $0.5\, kg$ travels on straight line path with velocity $v =\left(3 x ^{2}+4\right) m / s$. The net workdone by the force during its displacement from $x =0$ to $x =2\, m$ is$.......J$

By what reasons chemical energy produced in chemical process ?

A uniform chain of mass $m$ and length $L$ is originally placed mid-way on the top of a fixed smooth double-sided wedge (Figure- $A$). The length of each side of the wedge is $L$ . It is then given a slight push. The kinetic energy of the chain when the whole chain has just slid to the left side of the wedge (Figure- $B$), is :

A bullet of mass $200\,g$ having initial kinetic energy $90\,J$ is shot inside a long swimming pool as shown in the figure. If it's kinetic energy reduces to $40\,J$ within 1s, the minimum length of the pool, the bullet has a to travel so that it completely comes to rest is $.....m$

A ball is released from certain height. It loses $50\%$ of its kinetic energy on striking the ground. It will attain a height again equal to

A block of mass $2\, kg$ is placed on a rough inclined plane as shown in the figure $(\mu = 0.2)$ so that it just touches the spring. The block is allowed to move downwards. The  spring will be compressed to a maximum of .............. $\mathrm{cm}$