# Friction and its Effects Class-6th Goyal Brothers Physics Solutions

Friction and its Effects Class-6th Goyal Brothers Physics Solutions Chapter-3, Unit 2. We Provide Step by Step Answers of Objective, True False , Fill in the blanks, Match the following , Study Questions of Chapter- 3 , Force, Unit-2 (Friction and its Effects). Visit official Website for detail information about ICSE Board Class-6.

## Friction and its Effects Class-6th Goyal Brothers

Physics Solutions Chapter-3 (Unit 2)

 Board ICSE Class 6th Subject Physics Book Name Goyal Brothers Theme-3 Force Unit-2 Friction and its Effects Topic Solution of exercise questions Session 2023-24

### OBJECTIVE TYPE QUESTIONS

Physics Solutions Chapter-3, unit-2

#### A. Fill in the blanks :

1. Force of friction generally produces _heat_ energy
2. Force of friction increases with the increase in _weight_ of a body.
3. The SI unit of force is _Newton_.
4. The tool used to measure the magnitude of force is _spring balance_.
5. The force of friction between two surfaces can be reduced by _oiling_ them.

#### B. Write ‘True’ or ‘False’ for the following statements :

1. Force of friction is a consequential force. [T]
2. Force of friction is disadvantage in moving vehicle on the road. [F]
3. Friction wears out moving parts of a machine. [T]
4. The force required to lift a mass 1 kg in vertically upward direction is called newton. [F]
5. Streamlining reduces the friction between a body and a fluid. [T]

#### C. Statement given below are incorrect. write the correct  statement:

1. The tyres of vehicles are provided with deep grooves so as to decrease friction between the road and tyres.

Correct Statement: The tyres of vehicles are provided with deep grooves so as to increases friction between the road and tyres

2. Force of friction is an example of gravitational force.

Correct Statement: Force of friction is an example of consequential force.

3. Force of friction always acts in the direction of applied force.

Correct Statement: Force of friction always acts in the opposite direction of applied force.

4. The boats are streamlined to give them a better look.

Correct Statement: The boats are streamlined to give them least friction.

5. The rough surface offers very less friction.

Correct Statement: The rough surface offers very high friction.

#### 1. The  SI unit of force is :

(a) Newton (N)

(b) Kilogram force (Kgf)

(c) gramforce (gf)

(d) dyne

Ans: (a) Newton (N)

#### 2. Deep grooves in the tyre of a tractor :

(a) Decrease in friction

(b) Increase in friction

(c) Makes it stable

(d) Makes it attractive

Ans: (b) Increase in friction

#### 3. Force of friction :

(a) Increase with the increase in weight of body

(b) decrease with the increase in weight of body

(c) is not affected by the weight of body

(d) none of these

Ans: (a) Increase with the increase in weight of body

#### 4. Which is not the correct statement?

(a) reduces speed of body

(b) brings about wear and tear

(c) heats the body

(d) polishes the surface of body

Ans: (d) polishes the surface of body

#### (e) Lubricants

Column A Column B

### STUDY QUESTIONS

#### (a) What do you understand by the term Force of friction?

Answer: The force which acts opposite to the direction of motion of a body is known as the force of friction. For example, a ball rolling on a ground stops after sometime because of frictional force acting between the ground and the ball.

#### (b) When does force of friction come into play?

Answer: The frictional force comes into play when the two surfaces in contact experience a relative motion.

#### (c) If a force is applied towards East, in order to move a body, in which direction does the force of friction act?

Answer: Frictional force offers the resistance to the applied force opposing its motion. Thus, it always acts in the direction opposite to that of the object in motion i.e. towards west.

#### Question 2. Give two examples where the force of friction is an advantage.

Answer: Two examples where the force of friction is an advantage are :-

• It is used in automobile brakes in order to stop the vehicle
• It helps us to walk on the earth

#### Question 3. Give two examples where the force of friction is hindrance.

Answer: Two examples where the force of friction is an advantage are :-

• It wears out the sole of shoes
• It wears out the moving parts of machinery

#### Question 4. State two ways of increasing friction between two surfaces.

Answer: The two ways of increasing friction between two surfaces are :-

• Making the surfaces rough.
• By removing the lubrication between the surfaces in contact.

#### Question 5. State two ways of minimizing friction between two surfaces.

Answer: The two ways of minimizing friction between two surfaces are :-

• lubricating the surfaces.
• Streamlining the body.

#### Question 6. What do you understand by the term streamlining? Give few examples of streamlined bodies in (a) nature (b) Man-made objects.

Answer: Designing a body in such a way that it comes in minimum contact with air or water to ensure that the body experiences minimum frictional force, is called streamlining.

examples of streamlined bodies in nature is Fish.

examples of streamlined bodies in Man-made objects is Aeroplane.

#### Question 7. Why are the tyres provided with deep grooves on their surfaces ?

Answer: Tyre has a groove that increases the friction between them and the road. This enables the vehicle to make a firm grip on-road and prevent slipping. Grooved offers more friction to the ground which gives a better grip.

#### Question 8. Why does a knot tied in jute thread not slip easily , as compared to silk thread?

Answer: The fibrous surface of the jute thread has high friction, so the knot doesn’t slip easily. Silk thread is smooth and has low friction.

#### Question 9. Friction is necessary evil. Explain the statement by giving examples.

Answer: Force of friction brings about wear and tear in moving bodies. It produces heat and slows down moving body.A lot of energy is wasted in overcoming friction. However, if there were no friction, the bodies will either slip or will not move furthermore, the moving bodies will not stop. Even walking on the surface of earth would have been impossible. Thus, we can say that force of friction is a necessary evil.

#### Question 10. (a) State the common unit of force and define it.

Answer: The SI unit of force is newton. It is defined as the force that is required to accelerate a mass of 1 kg at the rate of 1 m/s2.

#### (b) Name the unit of force in SI system. How much mass can be lifted by this force in grams?

Answer: The unit of force in Standard International (S.I.) system is newton (N). 1 newton is the force required to lift the mass of 100 g vertically upward.

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