Applications of Friction

Q.

How is friction harmful?

Q.

What is dynamic friction

Q.

Why are grooves provided in the soles of shoes ?

Q.

Explain how, friction enables us to walk without slipping.

Q.

Why do gymnasts apply a coarse substance to their hands ?

Q.

Why are cars, aeroplanes and rockets streamlined?

Q.

What is frictional force?

Q. Why is writing with a chalk on glass not clear at all ?

Q.

State two advantages and two disadvantages of friction.

Q.

What is the relation between the direction of the force of friction and direction of motion?

Q. A block is sliding down a fixed inclined plane as shown below.

The direction of frictional force acting on the block is:

1. Downwards along the inclined plane
2. Upwards along the inclined plane
3. Vertically downwards
4. Vertically upwards

Q. A body shape which offers very little resistance to the flow of air (or water) around it is called:
(a) trimlined shape
(b) steamlined shape
(c) streaklined shape
(d) streamlined shape

Q. Without friction between our feet and the ground, walking would be impossible.

1. False
2. True

Q.

Why is it more difficult to walk properly on a well-polished floor ?

Q.

Name a force that reduces the efficiency of a machine.

Q.

Why there is a high amount of friction between polished surfaces?

Q.

Explain how can we walk more easily on a hard and rough surface than on a slippery surface.

Q.

Rahul went trekking with his friends. As they reached higher altitudes on the trek, they could feel their ears popping. Do you know the reason?

Q.

Explain why : (a) a pencil will write on paper but not on glass. (b) climbing a greasy pole is very difficult.

Q.

Why is it difficult to light a matchstick by striking it on a smooth surface ?

Q. Why friction always opposes the direction of the motion of a body?

Q.

Which of these statements describe the properties of friction?
A. Friction helps to induce magnetism
B. Friction acts in the opposite direction of relative motion.
C. Friction causes the surfaces in contact to wear away.
D. Friction produces heat energy.

1. A & B

2. A, C & D

3. C & D

4. B, C & D

Q. In which of the following cases, friction is acting as a friend?

1. Using pen for writing
2. Heating up a working mixer
3. Wearing of shoes
4. Noisy machines

Q. Friction helps us hold objects.

1. True
2. False

Q.

What prevents you from slipping every time you take a step forward?

Q.

State advantages of frictional force?

Q.

Give one example of when kinetic energy changes into heat energy.

Q.

The force applied on the brakes of a car results in the…………………

Q.

Due to which force does the wear and tear of machine parts occur?

Q.

Why are buses not designed to have a streamlined body?