Work, Energy and Power

An object falls from a height of 10 m above the ground. After striking the ground it loses 50% of its kinetic energy. The height upto which the object can rebounce from the ground is:

[Re-NEET 2024]

At any instant of time \(t\), the displacement of any particle is given by \(2t-1\) (SI unit) under the influence of force of \(5\mathrm{N}\). The value of instantaneous power is (in SI unit):

[NEET 2024]

A particle of mass M moves along a horizontal x-axis from x=0 to x=L. The coefficient of kinetic friction varies as a function of x as \({\mu }_{k}\)(x) = μ₀ − αx, where μ₀, α are constants of appropriate dimensions, so that \({\mu }_{k}\)(L)=0. The total work done by the frictional force during the motion is nμ₀MgL, where g is the acceleration due to gravity. The value of n is:

[Re-NEET 2026]

The power of a crane, which lifts a mass of 1000 kg to a height of 20 m in 10 s is : \(\left(g=9.8m/{s}^{2}\right)\)

The amount of work done to raise a mass ‘m’ from the surface of the Earth to a height equal to the radius of the Earth ‘R’, will be:

An object moving along horizontal x-direction with kinetic energy \(10\mathrm{J}\) is displaced through \(x=\left(3\hat{i}\right)\mathrm{m}\) by the force \(\vec{\mathrm{F}}=(-2\hat{i}+3\hat{j})\mathrm{N}\). The kinetic energy of the object at the end of the displacement x is :

An object moving along horizontal x-direction with kinetic energy \(10\mathrm{J}\) is displaced through \(x=\left(3\hat{i}\right)\mathrm{m}\) by the force \(\vec{\mathrm{F}}=(-2\hat{i}+3\hat{j})\mathrm{N}\). The kinetic energy of the object at the end of the displacement x is :

[Re-NEET 2024]

An object moving along horizontal x-direction with kinetic energy \(10\mathrm{J}\) is displaced through \(x=\left(3\hat{i}\right)\mathrm{m}\) by the force \(\vec{\mathrm{F}}=(-2\hat{i}+3\hat{j})\mathrm{N}\). The kinetic energy of the object at the end of the displacement x is :

[Re-NEET 2024]

An object moving along horizontal x-direction with kinetic energy \(10\mathrm{J}\) is displaced through \(x=\left(3\hat{i}\right)\mathrm{m}\) by the force \(\vec{\mathrm{F}}=(-2\hat{i}+3\hat{j})\mathrm{N}\). The kinetic energy of the object at the end of the displacement x is :

[Re-NEET 2024]

A point mass \( m \) is moved in a vertical circle of radius \( r \) with the help of a string. The velocity of the mass is \( \sqrt{7 \mathrm{gr}} \) at the lowest point. The tension in the string at the lowest point is

[Re-NEET 2020]

A body of mass ' \(m\) ' dropped from a height ' \(h\) ' reaches the ground with a speed of \(0.8 \sqrt{g h}\). The value of work done by the air-friction is:

[JEE Main 2021, 1 Sep (Shift 2)]

A constant power delivering machine has towed a box, which was initially at rest, along a horizontal straight line. The distance moved by the box in time ' \(t\) ' is proportional to:

[JEE Main 2021, 18 Mar (Shift 1)]

Water falls from a height of 60 m at the rate of 15 kg/s to operate a turbine. The losses due to frictional forces are 10% of energy. How much power is generated by the turbine? (g = 10 \(m/{s}^{2}\))

[NEET 2021]

The potential energy of a long spring when stretched by \(2\mathrm{cm}\) is U. If the spring is stretched by \(8\mathrm{cm}\), potential energy stored in it will be :

[NEET 2023]