Work-energy-power practice · Mixed difficulty

A man does a given amount of work in 10 sec. Another man does the same amount of work in 20 sec. The ratio of the output power of first man to the second man is

In which of the following cases, can the work done increase the potential energy?

If a block of mass $M$ is moving with a velocity $v$ along a straight path, when a constant force is applied, its kinetic energy is $\frac{1}{2} M v^2$. Then

Assertion (A): No work is done by the centripetal force acting on a body moving along the circumference of a circle
Reason (R): At any instant, the motion of the body is along the tangent to the circle where as the centripetal force is along the radius vector towards the centre of the circle

A man carries a load of 50 kg through a height of 40 m in 25 seconds. If the power of the man is 1568 W, his mass is

A body of mass 100 g is rotating in a circular path of radius r with constant velocity. The work done in one complete revolution is

Assertion: $\mathrm{KE}$ is conserved at every instant of (elastic) collision.

Reason: No deformation of matter occurs in elastic collision.

If potential energy is $U=3 x^2-2 x,$ then force will be:

Statement-1: A block of mass ' $M$ ' is placed on a moving railroad car moving with velocity ' $v$ '. The kinetic energy of the block is $\frac{1}{2} M v^2$ in all frames.

Statement-2: The kinetic energy of a system or body is different in different frames.

Assertion: For uniform circular motion it is necessary that the speed of the particle is constant.
Reason: There is no tangential force or tangential acceleration acting on particle in uniform circular motion.

A metre stick of mass 400 gram is pivoted at one end and displaced through an angle ${60^0}$. The increase in its potential energy is

A rubber ball falls from a height and comes to rest after several rebounds on the horizontal ground. If $e = 0.5$ and the ball travels a total distance of 25 m, the height from which it fell down is

A small $0.500-\mathrm{kg}$ object moves on a frictionless horizontal table in a circular path of radius $1.00 \mathrm{~m}$. The angular speed is $6.28 \mathrm{~rad} / \mathrm{s}$. The object is attached to a string of negligible mass that passes through a small hole in the table at the center of the circle. Someone under the table begins to pull the string downward to make the circle smaller. If the string will tolerate a tension of no more than $1280 \mathrm{~N}$, what is the radius of the smallest possible circle (in $\mathrm{cm}$) on which the object can move?

In an inelastic collision

According to work-energy theorem, the work done by the net force on a particle is equal to the change in its

A particle moving along a circular path the radial acceleration ${a}_{{r}}$ is proportional to time $t$. if ${a}_{{t}}$ is the tangential acceleration, then which of the following will be independent of time $t?$

The potential energy of a system increases if work is done

A body is moving in a circular path with a constant speed. It has

A car moves on a circular road. It describes equal angles about the centre is equal intervals of time. Which of the following statements about the velocity of the car is true?

A particle of mass ${m}$ is rotating by means of a string in a vertical circle. The difference in the tension at the bottom and top would be-

Assertion: A person working on a horizontal road with a load on his head does no work.
Reason: No work is said to be done, if directions of force and displacement of load are perpendicular to each other.

The potential energy of a particle of mass $1 \mathrm{~kg}$ is $U=10+(x-2)^2$. Here, $U$ is in joule and $x$ in metre on the positive $X$-axis. Particle travels upto $x=+6 \mathrm{~m}$. Choose the correct option.

You accidentally bump into a bookcase. It tilts briefly but then returns to upright, and you breathe a sigh of relief. When you first bumped the bookcase, its center of gravity moved

The area under the displacement-force curve gives

If the kinetic energy of a body is increased 2 times, its momentum will

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

A neutron moving with velocity v collides with a stationary $\alpha$-particle.The velocity of the neutron after the collision is

A body thrown vertically up with certain velocity. The power due to gravitational force is maximum

Two bodies of masses ${m_1}\,\,\mathrm{ and }\,\,{m_2}$ have same kinetic energy. The ratio of their momentum is

A uniform rope of mass $1 \mathrm{~kg}$ and length $1 \mathrm{~m}$ is lying on the ground. One end of the rope is pulled up by a worker with the constant velocity of $1 \mathrm{~m} / \mathrm{s}$. The average power supplied by the worker in pulling the entire rope just off the ground such that the rope becomes vertical is (take $g=10 \mathrm{~m} / \mathrm{s}^2$ )