Question

When a block is sliding on the horizontal surface by applying a force in the horizontal direction, the friction force on the block will depend on the:

a) Weight of the object

b) Area of contact between the block and the surface

1. Only a is correct
2. Only b is correct
3. Both a and b are correct
4. Neither a nor b is correct

Answer 1

Correct Answer - Option 1 : Only a is correct

CONCEPT:

Friction:

• The resistance offered by the surfaces that are in contact with each other when they move over each other is called friction.
• Factors affecting friction:
  1. ​​Types of surfaces in contact.
  2. The normal force between the two surfaces.
• The friction force between any two surfaces is given as,

⇒ F = μN

Where F = friction force, μ = co-efficient of friction, N = normal reaction and m = mass of the body

• The friction force between any two surfaces is independent of the surface area.

EXPLANATION:

• The friction force between any two surfaces is given as,

⇒ F = μN     -----(1)

• The normal reaction when the applied force is horizontal is given as,

⇒ N = mg     -----(2)

Where F = friction force, μ = co-efficient of friction, N = normal reaction and m = mass of the body

By equation 1 and equation 2,

⇒ F = μmg     -----(3)

• The friction force between any two surfaces is independent of the surface area.
• By equation 3 it is clear that the friction force depends on the weight of the body.
• Hence, option 1 is correct.