Work Energy And Power - Mechanics - Physics Previous Year Questions

A force of 20 N is applied on a body of mass 5 kg resting on a horizontal plane. The body gains a kinetic energy of 10 J after it moves a distance 2 m. The frictional force is

A particle of mass m is moving in a horizontal circle of radius R under a centripetal force equal to \(-\frac{A}{R^2}\) (A = constant). The total energy of the particle is

For motion under central forces, which quantity will be conserved?

Two masses of 1g and 9g are moving with equal kinetic energy. The ratio of magnitude of their momentum is

If kinetic energy of a body is increased by 300%, then percentage change in momentum will be

A particle of mass \(m\) is moving in a horizontal circle of radius \(r\) under a centripetal force given by \(\left(\frac{-K}{r^2}\right)\), where \(K\) is a constant. Then

If reaction is \(\mathrm{R}\) and coefficient of friction is \(\mu\), what is work done against friction in moving a body by distance \(\mathrm{d}\) ?

An electric motor raises a mass of \(1.5 \mathrm{~kg}\), a distance of \(1.128 \mathrm{~m}\) in time of \(4.79 \mathrm{~s}\). Calculate the power to an appropriate significant figures. (take \(g=9.81 \mathrm{~ms}^{-2}\))

An object of mass \(3 \mathrm{~kg}\) moves due to an applied constant force such that its position along \(\mathrm{X}\) axis is given by \(x=\frac{t^3}{3}\) where \(x\) is in meters and $t$ in seconds. The work done in 1 second is

A scooter moves with a speed of \(7 \mathrm{~ms}^{-1}\), on a straight road and is stopped by applying the brakes. Before stopping, the scooter travels \(10 \mathrm{~m}\). If the weight of the scooter is \(\mathrm{W}\), then the total resistance to the motion of the scooter will be

When water falls from a height of \(80 \mathrm{~m}\) at the rate of \(20 \mathrm{~kg} \mathrm{~s}^{-1}\) to operate a turbine the losses due to frictional force are \(20 \%\) of input energy. How much power is generated by the turbine?

The power of a gun which fires 120 bullet per minute with a velocity \(120 \mathrm{~ms}^{-1}\) is : (given the mass of each bullet is \(100 \mathrm{~g}\))

A particle is projected at an angle \(30^{\circ}\) with horizontal having kinetic energy \(K\). The kinetic energy of the particle at highest point is.

A long spring, when stretched by a distance \(x\), has potential energy \(U\). On increasing the stretching to \(n x\), the potential energy of the spring will be

A ball falls under gravity from a height of 10 m with an initial downward velocity u . It loses one third of its energy in collision and then rises back to 5 m . The initial velocity u is $\left(\mathrm{g}=10 \mathrm{~ms}^{-2}\right)$

A block of mass 1.5 kg moves along the floor of a hall with a speed of $5 \mathrm{~ms}^{-1}$. It strikes an uncompressed spring and compresses it till the block becomes motionless. If the force constant of the spring is $10000 \mathrm{Nm}^{-1}$ and the spring is compressed by 5 cm , calculate the effective force of kinetic friction.