CBSE Class 8 Science Chapter 9 Friction Question And Answers

CBSE Class 8 Science Chapter 9 Friction Fill In The Blanks

Question 1. Friction opposes the _________ between the surfaces in contact with each other.
Answer: Relative motion

Question 2. Friction depends on the _________ of surfaces.
Answer: Nature

Question 3. Friction produces _________.
Answer: Heat

Read And Learn More CBSE Class 8 Science Question And Answers

Question 4. Sprinkling of powder on the carrom board _________ friction.
Answer: Reduces

Question 5. Sliding friction is _________ than the static friction.
Answer: Less

Question 6. A spring balance is a device used for measuring the ________ acting on the object.
Answer: force

Question 7. On smooth surfaces, there are ________ number of irregularities. While on rough surfaces, there are an _______ number of irregularities.
Answer: Less, Large

Question 8. Friction can never be entirely ________.
Answer: Eliminated

Question 9. The soles of our shoes get worn out after a period of time. It is due to ________.
Answer: Friction

Question 10. ________ is produced by friction.
Answer: Heat

Question 11. Ball bearings reduce friction because they roll rather than ________.
Answer: Slide

Question 12. We pour a drop of oil on the hinge of the door to ________ friction.
Answer: Reduce

Question 13. Cars and speedboats are ________ to reduce drag.
Answer: Streamlined

CBSE Class 8 Science Chapter 9 Friction True Or False

Question 1. A fraction always works in the direction of the motion of the body.
Answer: False

Question 2. A soapy floor is slippery due to less friction.
Answer: True

Question 3. Friction increases with an increase in the smoothness of the surface.
Answer: False

Question 4. It is easier to roll the body over one another than to slide it.
Answer: True

Question 5. Friction enables vehicles to move on the ground.
Answer: True

Question 6. Fluid friction depends on the shape of an object placed in the fluid and the nature of the fluid.
Answer: True

Question 7. Athletes wear spikes to increase muscular force.
Answer: False

Question 8. A streamlined body shape helps in reducing drag.
Answer: True

Question 9. Frictional force does not depend on the nature of the
surfaces in contact
Answer: False

CBSE Class 8 Science Chapter 9 Friction Match The Columns

Question 1. Match Column 1 with those In Column 2

Answer: (a)-(2), (b)-(3), (c)-(5), (d)-(1), (e)-(4)

CBSE Class 8 Science Chapter 9 Friction Assertion-Reason Questions

The following questions consist of two statements: Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below.

1. Both A and R are true, and R is the correct explanation of A.
2. Both A and R are true, but R is not the correct explanation of A.
3. A is true, but R is false.
4. A is false, but R is true.

Question 1.

Assertion (A): The  Force of friction is smaller on smooth surfaces than on rough surfaces.
Reason (R): Static friction is greater than the sliding friction.

Answer: 2. The  Force of friction is smaller on smooth surfaces than on rough surfaces because on smooth surfaces, the irregularities present are much less compared to rough surfaces.

Question 2.

Assertion (A): Lubricants increase the friction force.
Reason (R): Friction is a necessary evil.

Answer: 4. Lubricants are the materials that minimise the friction force. Friction has advantages as well as disadvantages. That’s why it is called a necessary evil.

Question 3.

Assertion (A) Birds can fly easily in the sky.
Reason (R) Streamlined body helps them in minimizing the friction.

Answer: 1. A body shape that offers a small resistance to the flow of fluid around it, is called streamlined shape. Birds have streamlined shape by nature. That’s why, they fly easily in the air.

Question 4.

Assertion (A) It is difficult to push or pull a heavier object than a lighter object.
Reason (R) Interlocking of irregularities is more prevalent between heavy object surfaces than light object surfaces

Answer: 1. The interlocking of irregularities is more between heavy object surfaces than light object surfaces. That’s why it is difficult to push or pull heavier objects.

The following questions consist of two statements -Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below.

1. Both A and R are true, and R is the correct explanation of A.
2. Both A and R are true, but R is not the correct explanation of A.
3. A is true, but R is false.
4. A is false, but R is true.

Question 5.

Assertion (A): We often see that suitcases fitted with wheels are easy to pull.
Reason (R): Rolling friction is smaller than the static and sliding friction.

Answer: 1. Both A and R are true, and R is the correct explanation of A.

Question 6.

Assertion (A): Rocket and aeroplanes has a special body shape, i.e,. streamlined shape.
Reason (R): Streamlined shape helps an object reduce friction drag between the fluid and the object moving through it.

Answer: 1. Both A and R are true, and R is the correct explanation of A.