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

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 3

Friction Worksheet-1 Friction Worksheet-1 Friction is a type of:
A. contact force
B. non contact force
C. resistance force
D. Motion

Question 4

Which of the following statement is CORRECT?
A. rolling a body is easier than sliding
B. sliding body is easier than rolling
C. dragging body is easier than sliding
D. dragging body is easier than rolling

Question 5

In which of the following cases more friction is desirable?
A. movement of piston in a cylinder
B. braking of a vehicle
C. running on a track
D. all of these