Learn Class 8 Science - Friction

What is Friction? And what are the various factors which affect it? Are you curious to know more about things in detail?

About Friction

  • The friction force is also known as an external force.
  • It is the force that opposes relative motion.
  • LIKE: oppose between two surfaces.
  • Act only when it comes in touch with the bodies.

Types of Friction

Sliding Friction:

  • One which opposes the slide motion.
  • More minor as compared to static friction.

Static Friction:

  • The friction which is in 'rest.'
  • Force: 'Always equal & opposite to applied force.'

Rolling Friction:

  • Friction is present in two forces.
  • Smaller than sliding friction.

Effects of Friction

Friction:

  • It helps in the generation of heat.
  • It is always in motion.
  • Friction does wear and tear in tires.

Factors affecting Friction:

  • Nature of surface.
  • Polishing surfaces.
  • Normal reaction force.
  • Kinetic friction.
  • Spring balance.

These are factors that affect the frictional force. So make sure to keep all of the things in safe mode.

Pros:

  • The friction helps us to write on paper.
  • The friction helps to move on a road. I.e., friction between two surfaces.
  • Offer resistance to the actual motion.

Cons:

  • Wastage of energy.
  • The speed of the items becomes low.

Friction Sample Questions for Class 8

Question 1

Which of the following material is likely to have least friction?
A. Wood
B. Plastic
C. Glass
D. Paper

Question 2

Friction Worksheet-3 Friction Worksheet-3 Which of the following statement is TRUE?
A. static friction is more than dynamic friction
B. static friction is less than dynamic friction
C. static friction is equal to dynamic friction
D. there is no relationship between static and dynamic friction

Question 3

The surface of the head of a match stick and sides of a match box are deliberately made rough to:
A. increase friction
B. decrease friction
C. increase amount
D. decrease amount of heat

Question 4

A force of 5 N is required to move an object from rest. The value of static friction (f) is:
A. 5N
B. f >5N
C. f < 5N
D. 10 N

Question 5

When friction is acting in the direction of P, in which direction do you think the force is applied?
A. P
B. Q
C. R
D. S