Work Energy And Power - Mechanics - Physics Previous Year Questions

A force $(F)=-5 \hat{\mathbf{i}}-7 \hat{\mathbf{j}}+3 \hat{\mathbf{k}}$ acting on a particle causes a displacement $(s)=3 \hat{\mathbf{i}}-2 \hat{\mathbf{j}}+a \hat{\mathbf{k}}$ in its own direction. If the work done is 14 J , then the value of ' $a$ ' is

If the radius of the circular path and frequency of revolution of a particle of mass $m$ are doubled, then the change in its kinetic energy will be $\left(E_i\right.$ and $E_1$ are the initial and final kinetic energies of the particle respectively,)

A vehicle of mass \(m\) is moving with momentum \(p\) on a rough horizontal road. The coefficient of friction between the tyres and the horizontal road is \(\mu\). The stopping distance is (\(g=\) acceleration due to gravity)

Three bodies P, Q and R have masses 'm' kg, '2m' kg and '3m' kg respectively. If all the bodies have equal kinetic energy, then greater momentum will be for body/bodies.

A sphere of mass 25 gram is placed on a vertical spring. It is compressed by \(0.2 \mathrm{~m}\) using a force \(5 \mathrm{~N}\). When the spring is released, the sphere will reach a height of \(\left(\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^2\right)\) \(2 \mathrm{~m}\)

A bob of a simple pendulum of mass 'm' is displaced through 90\(^\circ\) from mean position and released. When the bob is at lowest position, the tension in the string is

A car of mass '\(m\)' moving with velocity '\(u\)' on a straight road in a straight line, doubles its velocity in time t. The power delivered by the engine of a car for doubling the velocity is

The kinetic energy of a light body and a heavy body is same. Which one of them has greater momentum?

A stone is projected vertically upwards with velocity 'V. Another stone of same mass is projected at an angle fo \(60^{\circ}\) with the vertical with the same speed \((\mathrm{V})\). The ratio of their potential energies at the highest points of their journey, is

$$\left[\sin 30^{\circ}=\cos 60^{\circ}=0.5, \cos 30^{\circ}=\sin 60^{\circ}=\frac{\sqrt{3}}{2}\right]$$

A ball of mass '\(\mathrm{m}\)' is dropped from a height '\(\mathrm{s}\)' on a horizontal platform fixed at the top of a vertical spring. The platform is depressed by a distance '\(h\)'. The spring constant is ( \(\mathrm{g}=\) acceleration due to gravity)

If a lighter body of mass '\(\mathrm{M}_1\)' and velocity '\(\mathrm{V}_1\)' and a heavy body (mass \(M_2\) and velocity \(V_2\) ) have the same kinetic energy then

Using variation of force and time given below, final velocity of a particle of mass \(2 \mathrm{~kg}\) moving with initial velocity \(6 \mathrm{~m} / \mathrm{s}\) will be

A stone is projected vertically upwards with speed '\(v\)'. Another stone of same mass is projected at an angle of \(60^{\circ}\) with the vertical with the same speed '\(v\)'. The ratio of their potential energies at the highest points of their journey is \(\left[\sin 30^{\circ}=\cos 60^{\circ}=0.5, \cos 30^{\circ}=\sin 60^{\circ}=\frac{\sqrt{3}}{2}\right]\)

If the momentum of a body of mass ' $m$ ' is increased by $20 \%$ then its kinetic energy increases by

A lead bullet moving with velocity ' V ' strikes a wall and stops. If $75 \%$ of its energy is converted into heat, then the increase in temperature is ( $\mathrm{s}=$ specific heat of lead, $\mathrm{J}=$ mechanical equivalent of heat)

For a particle moving in vertical circle, the total energy at different positions along the path [The motion is under gravity]

If the work done in blowing a soap bubble of volume ' V ' is ' W ', then the work done in blowing a soap bubble of volume ' 2 V ' will be

A body of mass 1 kg starts from rest and moves with uniform acceleration. In 2 seconds, its velocity is $10 \mathrm{~m} / \mathrm{s}$. The power exerted on the body in one second is

A simple pendulum of length L has mass m and it oscillates freely with amplitude A. At extreme position, its potential energy is ( $\mathrm{g}=$ acceleration due to gravity)

The power $(\mathrm{P})$ is supplied to a rotating body having moment of inertia ' I ' and angular acceleration ' $\alpha$ '. Its instantaneous angular velocity ' $\omega$ ' is