Work and Energy Science - Work and Energy

Which one of the following statements about power stations is not true?

1. Hydroelectric power stations use water to drive turbines.
2. In a power station, turbines drive generators.
3. Electricity from thermal power stations differs from that produced in hydroelectric power stations.
4. In hydroelectric power stations and thermal power stations, alternators produce electricity.

When an object falls freely towards the earth, then its total energy:

1. Increases.
2. Decreases.
3. Remains constant.
4. First increases and then decreases.

How much energy does a 100W electric bulb transfer in 1 minute?

1. 100J
2. 600J
3. 3600J
4. 6000J

Which one of the following is not the unit of energy?

1. Joule.
2. Newton-metre.
3. Kilowatt.
4. Kilowatt-hour.

Fill in the following blanks with suitable word:
The ability of a body to do work is called _____. The ability of a body to do work because of its motion is called _______.

Fill in the following blanks with suitable word:
The sum of the potential and kinetic energies of a body is called ______ energy.

Fill in the following blanks with suitable word:
Work is measured as a product of ________ and ________.

Fill in the following blanks with suitable word:
1 joule is the work done when a force of one ______ moves an object through a distance of one ______ in the direction of _______.

Fill in the following blanks with suitable word:
The work done on a body moving in a circular path is _______.

A cell converts one form of energy into another form. Name the two forms.

What are the units of (a) work, and (b) energy?

What kind of energy is possessedby the following?
A running car.

What kind of energy is possessedby the following?
A compressed spring.

What happens to the potential energy of a body when its height is doubled?

A bulb lights up when connected to a battery. State the energy change which takes place:

1. In the battery.
2. In the bulb.

The hanging bob of a simple pendulum is displaced to one extreme position B and then released. It swings towards centre position A and then to the other position C. In which position does the bob have:

1. Maximum potential energy?
2. Maximum kinetic energy?

Give reasons for your answer.

What are the quantities on which the amount on which the amount of work done depends? How are they related to work?

How fast should a man of 50kg run so that his kinetic energy be 625J?

Name the energy transfers which occur when:

1. An electric bell rings.
2. Someone speaks into a microphone.
3. There is a picture on a television screen.
4. A torch is on.

What are the various forms of energy?

When is the work done by a force on a body: (a) positive, (b) negative, and (c) zero?

Explain the transformation of energy in the following cases:

1. A ball thrown upwards.
2. A stone dropped from the roof of a building.

State and explain the law of conservation of energy with an example.

Two objects having equal masses are moving with uniform velocities of 2m/s and 6m/s respectively. Calculate the ratio of their kinetic energies.