If the water falls from a dam into a turbine wheel $19.6\, m$ below, then the velocity of water at the turbines, is ..................  $\mathrm{m} / \mathrm{s}$ (take $g = 9.8\, m/s^2$)

When work is done on a body by an external force, its

A particle of mass $500 \,gm$ is moving in a straight line with velocity $v=b x^{5 / 2}$. The work done by the net force during its displacement from $x=0$ to $x =4 \,m$ is ...................$J$ (Take $b =0.25 \,m ^{-3 / 2} s ^{-1}$ )

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$.......J$

A bullet of mass $20 \,g$ leaves a riffle at an initial speed $100 \,m / s$ and strikes a target at the same level with speed $50 \,m / s$. The amount of work done by the resistance of air will be ......... $J$

A force of $5\, N$, making an angle $\theta $ with the horizontal, acting on an object displaces it by $0.4\,m$ along the horizontal direction. If the object gains kinetic energy of $1\,J$, the horizontal component of the force is......$N$