The force acting on the system is represented against distance $r$ as shown. The potential energy of the system will be best represented by. (At $x=0,$ potential energy $=0$) 

In the figure shown the potential energy $U$ of a particle is plotted against its position $x$ from origin. Then which of the following statement is correct. A particle at:

A block of mass $m$ slides along the horizontal track with kinetic friction $\mu .$ A man pulls the block through a light rope which makes an angle $\theta$ with the horizontal as shown in the figure. The tension in the light rope is $T$ as shown. The block moves with constant speed $v$. Power delivered by the man to the block is:

Water is flowing in a river at rate $2.0 \mathrm{m} {\mathrm{s}}^{-1}$. The river is $50 \mathrm{m}$ wide and has an average depth $5.0 \mathrm{m}$. The power from the river flow current is,

(density of water $=1000 \mathrm{kg} {\mathrm{m}}^{-3}$, Assume no velocity gradient with depth)

There is a smooth fixed concave surface. A particle of mass $m$ Is released from $p.$ Find Kinetic energy as a function of $\theta$.

Radius of surface is. $R$