Cause of Friction

Q. Fill in the blanks.

1. Friction opposes the __________ between the surfaces in contact with each other.
2. Friction depends on the __________ of surfaces.
3. Friction produces __________.
4. Sprinkling of powder on the carrom board __________ friction.
5. Sliding friction is __________ than the static friction.

[5 marks]

Q. Friction can exist in outer space.

1. No
2. Yes

Q. The causes of friction are molecular adhesion, interlocking of surface irregularities and plowing effect.

1. True
2. False

Q. John carried out an experiment to find out how different road surfaces (P, Q, R and S) affect the stopping distance of a car travelling at 50 km/h. The result is tabulated below.

$\begin{array}{ccccc}\text{Type of road surface}& P& Q& R& S\\ \text{Stopping distance (m)}& 18& 15& 19& 27\end{array}$

Which surface provides maximum frictional force?

1. Q
2. R
3. S
4. P

Q. Which of the following statements is correct regarding friction between two surfaces in contact?

1. Smooth surfaces do not have friction
2. Friction is solely because of the interlocking of uneven surfaces
3. All the statements are incorrect
4. Friction exists between surfaces only if they are rough

Q.

What causes friction between two surfaces in contact when they try to slide past each other?

1. Gravitational attraction between the surfaces

2. Interlocking of irregularities present on the surfaces

3. Presence of atmosphere around the surfaces

4. Rigidity of the surfaces

Q. Why is there a high friction between two smooth glass pieces?

1. It is due to bond formation between the surfaces.
2. It is due to interlocking between the surfaces.
3. It is due to deformation of the surfaces.
4. It is due to irregularities present on the surfaces.

Q.

Friction can act between two bodies even when they are not in contact.

1. True

2. False

Q. Which of the following factors are responsible for friction?

1. Adhesion or stickiness
2. Plowing effect
3. Surface roughness
4. Density of the object

Q. Which factor is responsible for friction between two smooth and even surfaces?

1. Uneven interlocking of surfaces
2. Adhesion
3. Roughness
4. Smoothness