Work-energy-power practice · Easy

A ping-pong ball strikes a wall with a velocity of 12 m/s if the collision is perfectly elastic, find the velocity of ball after impact?

A boy carrying a box on his head is walking on a level road from one place to another on a straight road is doing no work. The statement is

Assertion: Collision between two billiard's ball is inelastic
Reason: Momentum remains conserve during the collision

If momentum of a body is increased by $20 \%$, then its kinetic energy increases by

There will an increase in potential energy of the system, if work is done upon the system by

A body is moving horizontally at a height of 9 m has its P.E = K.E. Then velocity of that body is

The kinetic energy of a body varies directly as square of time elapsed. The force acting varies directly as

The energy used by a 100 W bulb which is on for 10 hours is

A stone of mass 0.4 kg is attached to a string of length 3 m and is whirled in a horizontal circle. If the string can with stand a tension of 9 N. The maximum velocity with which the stone can be whirled is

How much water a pump of 3 kw can raise in one minute to a height of 9 m? $\left( {\mathrm{Take}\,g = 10\,\,m/{s^2}} \right)$

When two bodies stick after collision, the collision is known as

If the kinetic energy of a body is 5 times its momentum its velocity is

In which type of collision, the momentum of system is conserved?

When a body moves in a circular path, no work is done by the force since,

A person of mass 50 kg carrying a load of 20 kg walks up a stair case. If the width and height of each step are 0.25 m and 0.2 m respectively, the work done by the man in walking up 20 steps is

Two spheres whose radii are in the ratio 1:2 are moving with velocities in the ratio 3:4. If their densities are in the ratio 3:2, the ratio of their kinetic energies is,

If the kinetic energy of a body increases by 125%, the percentage increase in its momentum is

Statement I: The centripetal force and the centrifugal force never cancel out.
Statement II: They do not act at the same time.

A train is moving with a uniform velocity of $\left( {2\hat i - \hat j + 4\hat k} \right)\,m{s^{ - 1}}$. If the force required to overcome friction is $\left( {\hat i - 3\hat j + 2\hat k} \right)N$, the power of the engine is [watts]

A force of $\left( {3i + 4j + 5k} \right)N$act on a body and produced a displacement of $\left( {4i + 5j + 6k} \right)m.$ Then the amount of work done is

Two bodies $A$ and $B$ of same mass undergo completely inelastic one dimensional collision. The body $A$ moves with velocity $v_1$ while body $B$ is at rest before collision. The velocity of the system after collision is $v_2.$ The ratio $v_1: v_2$ is

If kinetic energy of a body is increased by $300 \%$ than percentage change in momentum will be

If two persons $A$ and $B$ takes 2 seconds and 4 seconds respectively to lift an object to the same height $h$ then ratio of their power is

A body is moving with a constant speed $v$ in a circle of radius $r$. Its angular acceleration is

Sand is falling on a conveyor belt at rate of 6 kg/s. The extra power required to move the belt with a velocity of 5 m/s is

A body constrained to move is Z direction is subjected to a force given by $\overline F = \left( {4i - 12j + 6k} \right)N$ What is the work done by the force is moving the body through a distance of 5 cm along Z-axis

The coefficient of restitution $e$ for a perfectly elastic collision is

In a circular motion of a particle, the tangential acceleration of the particle is given by $a_t=9 \mathrm{~m} / \mathrm{s}^2$. The radius of the circle is $4 \mathrm{~m}$. The particle was initially at rest. Time after which total acceleration of the particle makes an angle of $45^{\circ}$ with the radial acceleration is:

When a particle is moving in a vertical circle,

In the elastic collision of objects