A body is under the action of the equal and opposite forces, each of 5 N.The body is displaced by 2m.The work done is

A body at rest can have

A body starts from rest and acquires a velocity v in time T. The work done on the body in time t will be proportional to

The mass of a body P is twice that of body Q, but the speed of P is half of that of Q.The kinetic energies of P and Q are in the ratio of

If the speed of a motor car increases by six times, its kinetic energy will increase by

A car is moving with a uniform velocity of 54 kilometer per hour.What is the kinetic energy of a boy of mass 40kg sitting in the car?

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

What is the work done by the force of gravity on a satellite moving round the earth?Justify your answer.

A man holding a bucket of water on his head stands stationary. Is he doing any work? Give reason.

The human heart does 1.5J of work in every beat. How many times per minute does it beat, if its power is 2 W?

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?

Define the term energy.Give some examples of bodies possessing some energy.

A 100 W electric bulb is lighted for 2 hours every day and five 40W tubes are lighted for 4 hours everyday. Calculate
(i) the energy consumed for 60 days and the
(ii) cost of electricity consumed at the rate of Rs.3 per kWh.

Certain force acting on a 20 kg mass changes its velocity from 5 ms^-1 to 2 ms^-1 .Calculate the work done by the force.

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.

What kind of energy transformation takes place in the following devices?
(i) Electric heater
(ii) electric motor
(iii) dynamo
(iv) electric cell
(v) headphone
(vi) hydroelectric power station
(vii) steam engine 
(viii) solar battery
(ix) photoelectric cell

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.