Work and Energy Physics - Work and Energy

The negative of the work done by the conservative internal forces on a system equals the change in:

1. T​​​​​otal energy.
2. Kinetic energy.
3. Potential energy.
4. None of these.

A block of mass m slides down a smooth vertical circular track. During the motion, the block is in:

1. Vertical equilibrium.
2. Horizontal equilibrium.
3. Radial equilibrium.
4. None of these.

______ of a two particle system depends only on the separation between the two particles. The most appropriate choice for the blank space in the above sentence is:

1. Kinetic energy.
2. Total mechanical energy.
3. Potential energy.
4. Total energy.

A box is pushed through 4.0m across a floor offering 100N resistance. How much work is done by the resisting force?

A block of mass 2.00kg moving at a speed of 10.0m/s accelerates at 3.00m/s² for 5.00s. Compute its final kinetic energy.

A block of mass m moving at a speed v compresses a spring through a distance x before its speed is halved. Find the spring constant of the spring.

Is work-energy theorem valid in non-inertial frames?

A man moves on a straight horizontal road with a block of mass 2kg in his hand. If he covers a distance of 40m with an acceleration of 0.5m/s², find the work done by the man on the block during the motion.

A car weighing 1400kg is moving at a speed of 54km/h up a hill when the motor stops. If it is just able to reach the destination which is at a height of 10m above the point, calculate the work done against friction (negative of the work done by the friction).

A ball is given a speed v on a rough horizontal surface. The ball travels through a distance l on the surface and stops.

1. What are the initial and final kinetic energies of the ball?
2. What is the work done by the kinetic friction?

A particle is released from the top of an incline of height h. Does the kinetic energy of the particle at the bottom of the incline depend on the angle of incline? Do you need any more information to answer this question in Yes or No?

A uniform chain of mass m and length l overhangs a table with its two third part on the table. Find the work to be done by a person to put the hanging part back on the table.

Can kinetic energy of a system be increased without applying any external force on the system?

A block of mass 250g is kept on a vertical spring of spring constant 100N/m fixed from below. The spring is now compressed to have a length 10cm shorter than its natural length and the system is released from this position. How high does the block rise? Take g =10m/s².

In tug of war, the team that exerts a larger tangential force on the ground wins. Consider the period in which a team is dragging the opposite team by applying a larger tangential force on the ground. List which of the following works are positive, which are negative and which are zero?

1. Work by the winning team on the losing team.
2. Work by the losing team on the winning team.
3. Work by the ground on the winning team.
4. Work by the ground on the losing team.
5. Total external work on the two teams.

In one of the exercises to strengthen the wrist and fingers, a person squeezes and releases a soft rubber ball. Is the work done on the ball positive, negative or zero during compression? During expansion?

The US athlete Florence Griffith-Joyner won the 100m sprint gold medal at Seol Olympic 1988 setting a new Olympic record of 10.54s. Assume that she achieved her maximum speed in a very short-time and then ran the race with that speed till she crossed the line. Take her mass to be 50kg.

1. Calculate the kinetic energy of Griffith-Joyner at her full speed.
2. Assuming that the track, the wind etc. offered an average resistance of one tenth of her weight, calculate the work done by the resistance during the run.
3. What power GriffithJoyner had to exert to maintain uniform speed?

When you push your bicycle up on an incline the potential energy of the bicyle and yourself increases. Where does this energy come from?

Can static friction do nonzero work on an object? If yes, give an example. If no, give reason.

Can the work by kinetic friction on an object be positive? Zero?

A 250g block slides on a rough horizontal table. Find the work done by the frictional force in bringing the block to rest if it is initially moving at a speed of 40cm/s. If the friction coefficient between the table and the block is 0.1, how far does the block move before coming to rest?