DAV Class 6 Science Chapter 10 Question Answer – Work and Energy

The DAV Class 6 Science Book Solutions and DAV Class 6 Science Chapter 10 Question Answer – Work and Energy are essential study tools for DAV public school students in Class 6.

DAV Class 6 Science Ch 10 Question Answer – Work and Energy

DAV Class 6 Science Ch 10 Solutions – Work and Energy

Something To Know

A. Fill in the blanks.

Question 1.
The work done depends upon the ______ applied and the ______ produced.
Answer:
Force, displacement

Question 2.
______ is the capacity to do work.
Answer:
Energy

Question 3.
______ energy, stored in a battery, can be used to produce light in a torch.
Answer:
Chemical

Question 4.
______ is the main source of light energy.
Answer:
Sun

Question 5.
An electric bell produces sound from ______ energy.
Answer:
Electrical

B. Write True or False for the following statements.

1. Work is done whenever a force is applied on a given object.
2. A stationery ball does not possess kinetic energy.
3. A ball, raised to a height, is said to possess chemical energy.
4. The motion, of the blades of a fan, is due to mechanical energy.
5. Sound is a form of energy.
Answer:
1. Work is done whenever a force is applied on a given object. (False)
2. A stationery ball does not possess kinetic energy. (False)
3. A ball, raised to a height, is said to possess chemical energy. (False)
4. The motion, of the blades of a fan, is due to mechanical energy. (False)
5. Sound is a form of energy. (True)

C. Tick (✓) the correct option.

1. In which of the following situations, no ‘work’ is being done?
(a) Shifting a box of biscuits from a lower shelf to a higher shelf in the kitchen.
(b) Throwing a ball.
(c) Pushing a baby stroller on a road.
(d) Just holding a book in your hand for two minutes.
Answer:
(d) Just holding a book in your hand for two minutes,

2. The ability, or capacity, of a body to do work is known as
(a) Force
(b) Displacement
(c) Energy
(d) Motion
Answer:
(c) Energy

3. The form of energy, possessed by flowing water, is known as
(a) Potential energy
(b) Kinetic energy
(c) Chemical energy
(d) Light energy
Answer:
(b) Kinetic energy

4. The energy, associated with wind, is an example of
(a) Chemical energy
(b) Kinetic energy
(c) Potential energy
(d) Electrical energy
Answer:
(b) Kinetic energy

5. When a rubber band is stretched, it can be said to have gained
(a) Chemical energy
(b) Potential energy
(c) Kinetic energy
(b) Potential energy
Answer:
(b) Potential energy

D. Answer the following questions in brief.

Question 1.
Write the meaning of the following terms:
(a) Work
Answer:
When a force is applied on an object and a displacement is produce, then work is said to be done.

(b) Energy
Answer:
The capacity to do work is called energy.

Question 2.
State the conditions under which work is said to have been done.
Answer:
Two conditions are required for work to be done. The first condition is the applied force and the second condition is the displacement.

Question 3.
Name three different forms of energy.
Answer:
Three forms of energy are as follows:
(a) Mechanical energy
(b) Chemical energy
(c) Light energy

Question 4.
State the type of mechanical energy possessed by the following:

(a) A bullet fired from a gun.
Answer:
Kinetic energy

(b) The wound up spring of a toy car.
Answer:
Potential energy

(d) A moving bus.
Answer:
Kinetic energy

Question 5.
State two different uses of light energy.
Answer:
Two different uses of light energy are:
(a) Photosynthesis by green plants.
(b) Light is necessary for seeing an object.

E. Answer the following questions.

Question 1.
Is there any difference between ‘applying a force’ and ‘doing work ? Give reason for your answer.
Answer:
‘Applying a force’ is like a cause and ‘doing work’ is like a result of that cause. Force can be applied without work being done but work cannot be done without applying a force.

Question 2.
Explain, by giving an example, that a moving object can do work.
Answer:
When a stone hits a windowpane, it can break the glass of the pane. This happens because of the work being done by the moving stone. This example shows that a moving object can do work.

Question 3.
A porter keeps standing at a place while holding a suitcase of mass 30 kg over his head for five minutes. Has he done some work? Give reason for your answer.
Answer:
When someone is standing with some object on his bead, he is not doing a work. In this case, displacement does not happen in the object and hence no work is being done.

Question 4.
Define the term ‘energy’. Describe an activity to show the interrelationship between work and energy.
Answer:
The capacity to do work is called energy. The greater the amount of energy, more work can be done. The following activity can illustrate the interrelationship between work and energy. Take a cricket ball which is hard and heavy. Take a deep pan and fill it with sand. Now, drop the ball in the pan from a height of 1 metre.

Observe and measure the size of the depression which is formed in the sand because of the fallen ball. After that, drop the ball in the pan from a height of 2 metres. Once again observe the size of the depression in sand. You will notice that the size of the depression increases when the ball is dropped from more height. This happens because of higher potential energy possessed by the ball when it reaches a greater height. The size of depression in sand shows the relative amount of work being done.

Question 5.
Name a device which converts:

(a) Electrical energy into light energy.
Answer:
Electric bulb

(b) Sound energy into electrical energy.
Answer:
Microphone

Value Base Questions

Kshitij visited his native village during the summer vacation. While taking a stroll in the field, he saw a boy aiming his catapult at a bird. He asked the boy not to do so and to use his energy for helping, rather than harming, others.

Question 1.
Which quality of Kshitij’s behaviour do you appreciate?
Answer:
Caring attitude for animals

Question 2.
What kind of energy is possessed by the

(a) Stretched string of the catapult?
Answer:
Potential energy

(b) The stone when it gets released from the catapult?
Answer:
Kinetic energy

Question 3.
Do you think that Kshitij did the right thing by asking the boy not to hit the bird?
Answer:
Yes. Kshitij was right in asking the boy not to hit the bird. We should not harm or kill innocent creatures.

Question 4.
Give your suggestions about how one can use his/her energy for helping, rather than harming, others?
Answer:
We can use our energy in feeding a bird or a stray dog, rather than hitting them. We can use our energy in helping others.

Something To Do

Question 1.
List some examples in which no work is done on a body though a force acts on it.
Answer:
When a person is trying to push the wall. When a person is standing at a place with a heavy load over his head.

Question 2.
We can easily perform several tasks, like opening a bottle, or lifting heavy objects, easily by using ‘simple machines’. Suggest some activities/tasks, which illustrate the usefulness of some simple machines.
Answer:
There can be many examples, like trying to unscrew a nut with bare hands and then with a wrench.

Question 3.
The law of conservation of energy states that ‘energy can neither be created nor be destroyed’; it can only be transformed from one form to another. Keeping this law in mind, complete the table given below for the type of energy transformation that takes place in the different devices listed there.

Device	Transformation of Energy
Device	From	To
Electric cell		Electrical energy
Electric bulb	Electrical energy
Ceiling fan	Electrical energy
Drum		Sound energy
Clothes dryer	Electrical energy
Headphone		Sound energy
Electric mixer	Electrical energy
A ‘stone’ released from a stretched catapult.		Kinetic energy

Answer:

Device	Transformation of Energy
Device	From	To
Electric cell	Chemical energy	Electrical energy
Electric bulb	Electrical energy	Light energy
Ceiling fan	Electrical energy	Kinetic energy
Drum	Mechanical energy	Sound energy
Clothes dryer	Electrical energy	Mechanical energy
Headphone		Sound energy
Electric mixer	Electrical energy	Mechanical energy
A ‘stone’ released from a stretched catapult.	Potential energy	Kinetic energy

Question 4.
Take a 15-minute ‘minifield trip’ of your school library, computer lab, science laboratory, canteen, etc. Spend these 15 minutes making observations about the energy transformations taking place in the different devices being used there. List your observations in your science notebook.
Answer:
Do it yourself.

DAV Class 6 Science Chapter 10 Solutions – Work and Energy

I. Fill in the blanks.

Question 1.
Work done is given as ______ of force and displacement.
Answer:
Product

Question 2.
The unit of force is ______
Answer:
Newton

Question 3.
The unit of work done is ______
Answer:
Newton metre

Question 4.
An arrow held in a stretched bow possesses ______ energy.
Answer:
Potential

Question 5.
An arrow moving towards the dart board possesses ______ energy.
Answer:
Kinetic

Question 6.
Food possesses ______ energy.
Answer:
Chemical

II. Tick (✓) the correct option.

1. Which of the following is doing a work?
(a) A student is reading a book.
(b) A chess player is thinking.
(c) A child is pulling a toy car.
(d) A rock atop a mountain.
Answer:
(c) A child pulling a toy car

2. Which of these is possessing potential energy?
(a) A ball kept on a table
(b) A ball being hit by a batsman
(c) A ball breaking a glass pane
(d) All of these
Answer:
(a) A ball kept on a table

3. Which of these changes chemical energy into electrical energy?
(a) Chemical reaction
(b) Electric cell
(c) Photosynthesis
(d) Food
Answer:
(b) Electric cell

4. Which of these changes electrical energy into sound energy?
(a) Tape recorder
(b) Microphone
(c) Speaker
(d) Electric engine
Answer:
(c) Speaker

5. What is the SI unit of work done?
(a) Newton
(b) Metre
(c) Newton metre
(d) None of these
Answer:
(c) Newton metre

III. Answer these questions.

Question 1.
What do you understand by work done? Explain.
Answer:
When a force; acting on a body; causes some displacement in the body, it is said that the work is done. If F is the force and S is the displacement, then work done can be given as follows:
W = F x S

Question 2.
What is potential energy? Explain with an example.
Answer:
The energy possessed by an object because of its position is called potential energy. For example; a stone which is kept at a height can break something if it falls on something. This would happen because of the potential energy in the stone due to its position at a height.

Question 3.
What is chemical energy? Explain with an example.
Answer:
Certain substances produce energy because of some chemical reaction. Such form of energy is called chemical energy. For example; when a matchstick is rubbed against the matchbox, it produces fire because of a particular chemical reaction.

Question 4.
When a glass marble is shot from a catapult, it can break a windowpane. Why?
Answer:
When a glass marble is shot from a catapult, it possesses kinetic energy. The kinetic energy in the glass marble can do enough work to break a windowpane and that is why the windowpane gets broken.

IV. Projects

Question 1.
Make a list of objects in which electrical energy is converted into mechanical energy.
Answer:
Do it yourself.

Question 2.
Make a list of objects in which mechanical energy is converted into sound energy.
Answer:
Do it yourself.