Short Q/A Work and Energy

A bullet is fired from a gun, penetrates into a sand wall, and stops. Where does its kinetic energy go?

When a bullet is fired from a gun, its kinetic energy is initially high due to its velocity. Upon striking the sand wall, the bullet penetrates and eventually stops. The kinetic energy of the bullet is converted into several forms of energy. Primarily, it is transformed into heat energy, which is absorbed by the bullet, … Read more

A car has kinetic energy ‘Eₖ’. By what factor would its kinetic energy change if its velocity is doubled?

Kinetic energy is proportional to the square of the velocity of an object. The formula for kinetic energy is given by Ek=1/2mv2, where m is the mass and v is the velocity. If the velocity of the car is doubled, the kinetic energy will increase by a factor of four. This is because (2v)2=4v2, so … Read more

Work done on a body either speeds it up or slows it down. Keeping this in mind, explain how much work is done by centripetal force on an orbiting satellite?

Centripetal force does no work on an orbiting satellite. This is because work is only done when a force has a component in the direction of the displacement of the object. In the case of a satellite in orbit, the centripetal force acts perpendicular to the satellite’s direction of motion (which is tangential to its … Read more

Does the work done in raising a box up in a building depend upon how fast it is raised up? Through which path? To how much height?

The work done in raising a box depends on the height to which it is lifted and not on the speed at which it is raised. Work is defined as the product of the force applied to move an object and the distance over which it moves in the direction of that force. The force … Read more