Consider an elliptically shaped rail $P Q$ in the vertical plane with $O P=3 \ m$ and $OQ =4 \ m$. A block of mass $1 \ kg$ is pulled along the rail from $P$ to $Q$ with a force of $18 \ N$, Which is always parallel to line $PQ$ (see the figure given). Assuming no frictional losses, the kinetic energy of the block when it reaches $Q$ is $(n \times 10)$ joules. The value of $n$ is (take acceleration due to gravity $=10 \ ms ^{-2}$ )

Two bodies moving towards each other collide and move away in opposite directions. There is some rise in temperature of bodies because a part of the kinetic energy is converted into

A particle of mass $10\, g$ moves along a circle of  radius $6.4\, cm$ with a constant tangential acceleration. What is the magnitude of this acceleration if the kinetic energy of the particle becomes equal to $8 \times 10^{-4}\,J$ by the end of the second revolution after the beginning of the motion $?$ .............. $\mathrm{m} / \mathrm{s}^{2}$

The total work done on a particle is equal to the change in its kinetic energy. This is applicable

A body of mass $1\,kg$ is thrown upwards with a velocity $20\, m/s.$ It momentarily comes to rest after attaining a height of $18\, m.$ How much energy is lost due to air friction ? ........... $\mathrm{J}$ $ (g = 10 \,m/s^2)$

A force acts on a $2\,kg$ object so that its position is given as a function of time as $x= 3t^2 + 5.$ What is the work done by this force in first $5\,seconds$ ? ................ $\mathrm{J}$