Frictional force

Q.

Direction of force of friction is always in the same direction of motion.

1. True

2. False

Q. Question 11
Two boys are riding their bicycles on the same concrete road. One has new tyres on his bicycle while the other has tyres that are old and used. Which of them is more likely to skid while moving through a patch of the road which has lubricating oil spilled over it?

Q. A car which is stuck in mud can be pulled out with the aid of a wooden plank. The function of the wooden plank is to _________.

1. increase friction

2. decrease friction

3. give direction to the car

4. reduce weight of the car

Q.

What are the two important properties of friction?

Q.

A coin flicked across a table stops because

1. no friction acts on it

2. it is very heavy

3. the table exerts a frictional force on it

4. the Earth attracts it.

Q.

"Friction is a force which opposes the relative motion between two objects”.

1. True

2. False

Q. Which of the following statements define friction appropriately?

1. A force that resists the motion of surfaces.
2. A force that resists the relative motion of surfaces.
3. A force that does not depend on the nature of the surface.
4. A force that is non-contact in nature.

Q.

Which of the following are effects of frictional force?

1. Wearing out of soles of shoes

2. A rolling ball coming to a halt

3. Leaves falling on the Ground

4. A plastic ruler attracting small bits of papers

Q.

Does friction opposes motion or relative motion?

Q.

It is difficult to walk on a wet road. Explain.

Q.

There are three paths ahead of you, made with gravel, bricks, and smooth marbles each. Which path should you avoid to prevent yourself from slipping.

Q.

Look at the given figure and answer the following questions:

If the boy is pushing the box from right to left, the force of friction will act from ...............….

Q.

There are two surfaces, A and B in contact with each other. Consider the following situations:

Situation I: Both A and B are at rest.
Situation II: A is moving while B is at rest and A is over B.
Situation III: A is at rest while B is moving and A is over B.
Situation IV: A is at rest while B is moving and B is over A.

In which of the given situations would you expect frictional force to come into play?

1. Situation I

2. Situation II

3. Situation III

4. Situation IV

Q.

Friction

1. promotes motion

2. opposes motion

3. acts in the direction of motion

4. is always a nuisance

Q. why pseudo force are also called inertial force?

Q.

it is difficult to walk on muddy floor or slippery floor.(give examples for each)

Q.

A book placed on the desk is pushed to the right, in which direction will the force of friction act?

1. right

2. left

3. vertically upwards

4. vertically downwards

Q. When two surfaces are polished, the friction coefficient between them decreases. But the friction coefficient increases and becomes very large if the surfaces are made highly smooth. Explain.

Q.

Define friction.

Q.

WHY CANNOT WE WRITE ON GLASS WITH A PENCIL?