Work done is measure by

Joule is the unit of

Ns is equivalent to

A body is acted upon by a force which is inversely proportional to the distance covered (S).The work done will be proportional to

Kg m² s^-2 is associated with

A wound watch spring has

The kinetic energy of a body decreses by 10%.What is the percentage decrease in momentum? 

If the mass of a body is doubled, its kinetic energy of 1 joule relative to the ground when it is at a height of

Two particles of masses 1 g and 4 g have equal kinetic energies.What is the ratio between their momenta?

If a stone of mass m falls a vertical d, the decrease in gravitational potential energy is

When do we say that work is done?

What is the kinetic energy of an object?

What is the work done when the direction of displacement and the direction of force F acting on a body are perpendicular to each other?

A pair of bullocks exerts a force of 140N on a plough.The field being ploughed is 15 m long.How much work is done in ploughing the length of the field?

How does an object with energy do work?

Two bodies of equal masses move with uniform velocities of 2v and 3v respectively.Find the ratio of their kinetic energies.

Explain that the flying bird has potential and kinetic energy and give their expressions.

Discuss whether or not work is done in the following cases:
(i) When we twist a wire.
(ii) When we press a football.
(iii) When we push a table.
(iv) When a person carries a handbag and walks on a level road.
(v) When a person holds a book in his hand and keeps it stationary.

A car weighing 1000 kg and travelling at 30 m/s stops at a distance of 50 m decelerating uniformly. What is the force exerted on it by the brakes?What is the work done by the brakes?

A body of mass 25 kg is raised to the top of a building 10 m high and then dropped freely under gravity.
(a) Calculate the work done in raising the body to the top of the building.
(b) What is the value of the gravitational potential energy at the top of the building?
(c) By what factor will the gravitational potential energy of the same body increase if it is raised to the top of a multistorey building 30 m high?
(d) When will the kinetic energy of the body be maximum?

Define 1 watt of power.

An object of mass 40 kg is raised to a height of 5m above the ground.What is its potential energy?If the object is allowed to fall, find its kinetic energy when it is half-way down.

Define the term work.State the conditions that need to be satisfied for work to be done.Give some situations in which work is done.

Write the various energy transformations that occur in the following cases:
(a) Moving a car
(b) Going up in an escalator
(c) Rotating of an electric motor
(d) Release of an arrow from a bow
(e) Lighting of an electric bulb
(f) Tuning of an FM radio receiver
(g) Gas stove burner.

(i) A battery lights a bulb.Describe the energy changes involved in the process.
(ii) Calculate the amount of work needed to stop a car of 500 kg moving at a speed of 36 kmh^-1.