# Frank solutions for Class 9 Physics ICSE chapter 3 - Laws of Motion [Latest edition]

## Chapter 3: Laws of Motion

Exercise
Exercise [Pages 113 - 114]

### Frank solutions for Class 9 Physics ICSE Chapter 3 Laws of Motion Exercise [Pages 113 - 114]

Exercise | Q 1 | Page 113

What do you mean by inertia of motion?

Exercise | Q 2 | Page 113

Give one example each of inertia of rest and inertia of motion.

Exercise | Q 3 | Page 113

The greater is the __________ the greater is the inertia of an object.

Exercise | Q 4 | Page 113

Name the different kinds of inertia an object can possess. Give an example of each.

Exercise | Q 5 | Page 113

Define one Newton. How much maximum acceleration can it produce in a mass of 1 kg?

Exercise | Q 6 | Page 113

The acceleration produced by a force in an object is directly proportional to the applied _________ And inversely proportional to the _________ Of the object.

Exercise | Q 7 | Page 113

What is the SI unit of force?

Exercise | Q 8 | Page 113

Name the physical quantity associated with N kg-1.

Exercise | Q 9 | Page 113

The CGS unit of force is dyne:
∴1 N = __________ dyne

Exercise | Q 10 | Page 113

When a sports car and a loaded van are travelling at a speed of 50 km/h, which vehicle requires more force to stop?

Exercise | Q 11 | Page 113

What is the acceleration produced by a force of 12 N exerted on an object of mass 4 kg?

Exercise | Q 12 | Page 113

What is the ratio of SI to CGs units of force?

Exercise | Q 13 | Page 113

Write the SI unit of momentum.

Exercise | Q 14 | Page 113

Define momentum of a body.

Exercise | Q 15 | Page 113

Name the physical quantity associated with the motion of a body.

Exercise | Q 16 | Page 113
Momentum is possessed by bodies in ______.
Exercise | Q 17 | Page 113

Which has more momentum: a fast pitched soft ball or a soft pitched soft ball?

Exercise | Q 18 | Page 113

What is the ratio of SI units to CGS units of momentum?

Exercise | Q 19 | Page 113

What will be the momentum of a body at rest?

Exercise | Q 20 | Page 113

State Newton's third law of motion.

Exercise | Q 21 | Page 113

What do you mean by action?

Exercise | Q 22 | Page 113

Do action and reaction act on the same body?

Exercise | Q 23 | Page 113

ame the law of motion which gives the definition of force.

Exercise | Q 24 | Page 113
A boy jumps to a dock from a boat. The boat moves away from the dock. Which law explains the statement?
Exercise | Q 25 | Page 113

Is force a scalar or a vector quantity?

Exercise | Q 26 | Page 113

If a number of forces act on a stationary body at the same point, then what do you conclude from it?

Exercise | Q 27 | Page 113

Why do passengers tend to fall sideways when the bus takes a sharp turn?

Exercise | Q 28 | Page 113

Why are passengers thrown in the forward direction when a running bus stops suddenly?

Exercise | Q 29 | Page 113

Why do passengers tend to fall backward when it starts suddenly?

Exercise | Q 30 | Page 113

Can internal forces change the velocity of a body?

Exercise | Q 31 | Page 113

Why do the dust particles come out of a hanging carpet when it is beaten with a stick?

Exercise | Q 32 | Page 113

Why is a tree shaken to get its fruit down?

Exercise | Q 33 | Page 113

Which would require a greater force: accelerating a 10 g mass at 5 ms-2, or accelerating a 20 g mass of 2 ms-2?

Exercise | Q 34 | Page 113

The velocity-time graph of a coin moving on a table is shown in the below figure. If the mass of the coin is 20 g, then how much force does the table exert on the coin to bring it to rest?

Exercise | Q 35 | Page 114

An object undergoes an acceleration of 8 ms-2 starting from rest. Find the distance travelled in 5 seconds.

Exercise | Q 36 | Page 114

A truck rolls down a hill with constant acceleration after starting from rest. It travels a distance of 100 m in 10 s. find its acceleration. Find the force acting on it, if its mass is 5 metric tons. (tonne)

Exercise | Q 37 | Page 114

Name the physical entity used for quantifying the motion of a body.

Exercise | Q 38 | Page 114

Why do you feel a backward jerk on your shoulder when you fire a gun?

Exercise | Q 39 | Page 114

How does a person move forward during swimming?

Exercise | Q 40 | Page 114

Name the principle involved in the working of a jet engine.

Exercise | Q 41 | Page 114

Is the statement correct?
A rocket can propel itself in vacuum.

Exercise | Q 42 | Page 114

Since action and reaction forces are always equal in magnitude and opposite in direction, how can anything be ever accelerated?

Exercise [Pages 125 - 126]

### Frank solutions for Class 9 Physics ICSE Chapter 3 Laws of Motion Exercise [Pages 125 - 126]

Exercise | Q 1 | Page 125

Who stated the law of gravitation?

Exercise | Q 2 | Page 125

State Newton's law of gravitation.

Exercise | Q 3 | Page 125

Distinguish between gravity and gravitation

Exercise | Q 4 | Page 125

Define acceleration due to gravity.

Exercise | Q 5 | Page 125

Write the relation between g and G

Exercise | Q 6 | Page 125

Define the constant of gravitation.

Exercise | Q 7 | Page 125

What are the SI units of constant of gravitation?

Exercise | Q 8.1 | Page 125

How will the force of gravitation between two objects change if the distance between them is:
Halved

Exercise | Q 8.2 | Page 125

How will the force of gravitation between two objects change if the distance between them is:
Doubled

Exercise | Q 8.3 | Page 125

How will the force of gravitation between two objects change if the distance between them is:

Exercise | Q 8.4 | Page 125

How will the force of gravitation between two objects change if the distance between them is:
Infinite

Exercise | Q 8.6 | Page 125

How will the force of gravitation between two objects change if the distance between them is:
Almost zero

Exercise | Q 9 | Page 125

All objects in the universe attract each other along the line joining their________.

Exercise | Q 10 | Page 125

The force of attraction between any two material objects is called __________.

Exercise | Q 11 | Page 125

The gravitational force of the earth is called earth's __________.

Exercise | Q 12 | Page 125

he gravity is a particular case of _________.

Exercise | Q 13 | Page 125

The value of G is extremely____________.

• Small

• large

• large

Exercise | Q 14 | Page 125

Is the law of gravitation applicable in case of the sun and the moon?

Exercise | Q 15 | Page 125

Given:
Mass of the earth = 6X1024kg.
Radius of the earth = 6.4 X 106 m
G = 6.7 x 1011Nm2kg-2
Using this data, calculate the force of gravity due to the earth acting on a 100 kg person stannding on the ground.

Exercise | Q 16 | Page 125

Why do objects fall towards the earth?

Exercise | Q 17 | Page 125

Why don't you feel the force of attraction between your friend sitting close to you and yourself?

Exercise | Q 18.1 | Page 125

A ball is thrown up with a speed of 4.9 ms-1.
Calculate the maximum height it would gain before it begins to fall.

Exercise | Q 18.2 | Page 125

A ball is thrown up with a speed of 4.9 ms-1.
Calculate the time it takes to reach this height.

Exercise | Q 18.3 | Page 125

A ball is thrown up with a speed of 4.9 ms-1.
Prove that the time of ascent is equal to the time of descent.

Exercise | Q 19 | Page 125

What is the relation between 'g' and 'G'?

Exercise | Q 20 | Page 125

What is the value of g at the surface of the earth?

Exercise | Q 21 | Page 125

When some rock is brought to the earth from the surface of the moon, Will its mass and weight change?

Exercise | Q 22 | Page 125

Where will you weigh more: at the centre of the earth or at the surface of the earth?

Exercise | Q 23 | Page 125

Name an instrument used to measure the mass of a body.

Exercise | Q 24 | Page 125

Name the instrument by which the weight of a body can be measured.

Exercise | Q 25 | Page 125

Where do you weigh more: at the poles or at equator?

Exercise | Q 26 | Page 125

How are kgwt and N related to each other?

Exercise | Q 27 | Page 125

Where will you weigh more: at the moon's surface or at the earth's surface?

Exercise | Q 28 | Page 125

Does the force of gravitation between two objects depend on the medium between them?

Exercise | Q 29 | Page 125

What will happen to the gravitational force of attraction between two objects if the mass of each is doubled and the distance between them is also doubled?

Exercise | Q 30 | Page 126

In vacuum, all freely falling objects have the same force. Is it true?

Exercise | Q 31 | Page 126

What is meant by the equation :
g= Gxxm/r^2
where the symbols have their usual meanings.

Exercise | Q 32 | Page 126

State whether the below statement is True or False.
Neglecting air resistance, a body falling freely near the earth's surface has a constant acceleration.

Exercise | Q 33 | Page 126
At which of the following locations, the value of g is the largest?
• On top of the Mount Everest

• On top of Qutub Minar

• At a place on the equator

• A camp site in Antarctica

Exercise | Q 34 | Page 126

At what height above the earth's surface would the value of acceleration due to gravity be half of what it is on the surface? Take the radius of earth to be R.

Exercise [Pages 128 - 131]

### Frank solutions for Class 9 Physics ICSE Chapter 3 Laws of Motion Exercise [Pages 128 - 131]

Exercise | Q 1 | Page 128

What is a force?

Exercise | Q 2 | Page 128

Define one Newton.

Exercise | Q 3 | Page 128

What is the relation between Newton and dyne?

Exercise | Q 4 | Page 128

Is force a scalar quantity?

Exercise | Q 5 | Page 128

A force can produce ________, In an object at rest. It can __________ an object and change its __________ of motion.

Exercise | Q 6.1 | Page 128

What does a force do in the following case?
You pull the skin of your arm

Exercise | Q 6.2 | Page 128

What does a force do in the following case?
You twist a piece of rubber.

Exercise | Q 6.3 | Page 128

What does a force do in the following case?
You apply brakes to a running car.

Exercise | Q 6.4 | Page 128

What does a force do in the following case?
You catch a kicked ball.

Exercise | Q 7 | Page 128

Can every force produced motion in every type of body?

Exercise | Q 8 | Page 128

The amount of inertia of a body depends on its _________.

Exercise | Q 9 | Page 128

You can change the direction in which an object is moving by___________.

Exercise | Q 10 | Page 128

A man riding on a car has ___________ Inertia.

Exercise | Q 11 | Page 128

What do you mean by inertia of rest?

Exercise | Q 12.1 | Page 128

Name and state the action and reaction in the following case:
A book lying on a table.

Exercise | Q 12.2 | Page 128

Name and state the action and reaction in the following case:
A person walking on the ground.

Exercise | Q 12.3 | Page 128

Name and state the action and reaction in the following case:
Hammering a nail.

Exercise | Q 12.4 | Page 128

Name and state the action and reaction in the following case:
Firing a bullet from a gun.

Exercise | Q 12.5 | Page 128

Name and state the action and reaction in the following case:
Pushing a wall.

Exercise | Q 13.1 | Page 128

Give two examples of the following:
Inertia of rest

Exercise | Q 13.2 | Page 128

Give two examples of the following:
Inertia of motion

Exercise | Q 14 | Page 128

What causes motion in a body?

Exercise | Q 15 | Page 128

What do you mean by linear momentum of a body?

Exercise | Q 16 | Page 128

Write the SI unit of momentum.

Exercise | Q 17 | Page 128

Give qualitative definition of force on the basic of Newton's first law of motion.

Exercise | Q 18 | Page 128

State Newton's first law of motion.

Exercise | Q 19 | Page 129

Which of the following has the largest inertia?

• A car

• A truck

• A cricket ball

• A ball pen

Exercise | Q 20 | Page 129

Why is it advantageous to turn before taking a long jump?

Exercise | Q 21 | Page 129

Why does a ball moving on a table top eventually stops?

Exercise | Q 22 | Page 129

Name the physical quantity which equals the rate of change of linear momentum.

Exercise | Q 23 | Page 129

State Newton's second law of motion. Is Newton's first law of motion contained in Newton's second law of motion?

Exercise | Q 24 | Page 129

Define one newton. What is the ratio of SI to CGS units of force?

Exercise | Q 25 | Page 129

Prove that 1 N = 105 dyne. Is 1 N same as 1 kgms-2?

Exercise | Q 26 | Page 129

Two equal and opposite forces acting at the same point on a stationary body. Will the body move? Give reason to explain your answer.

Exercise | Q 27 | Page 129

Two equal and opposite forces act on a moving body. How is its motion affected?

Exercise | Q 28 | Page 129

State Newton's third law of motion. Explain, the motion of a rocket with the help of Newton's third law of motion.

Exercise | Q 29 | Page 129

A boy pushes a wall with a force of 30 N towards east. What force is exerted by the wall on the boy?

Exercise | Q 30 | Page 129

Name the scientist who first stated the law of inertia.

Exercise | Q 31 | Page 129

State the law of gravitation. Why is it called universal?

Exercise | Q 32 | Page 129

What is the difference between gravity and gravitation?

Exercise | Q 33 | Page 129

Where will a person weigh more: at Simla or at Delhi?

Exercise | Q 34 | Page 129

Name the instrument used to measure the weight of a body.

Exercise | Q 35 | Page 129

Gravity is another kind of ________. It exerts all through the ________. The Sun's gravity keeps the ___________ in their orbits. Gravity can only be felt with very large ________.

Exercise | Q 36.1 | Page 129

Explain why:
Objects fall to the earth.

Exercise | Q 36.2 | Page 129

Explain why:
The atmosphere does not escape.

Exercise | Q 36.3 | Page 129

Explain why:
A moon rocket needs to reach a certain velocity.

Exercise | Q 37 | Page 129

Explain the difference between g and G.

Exercise | Q 38 | Page 129

What do you understand by the free fall?

Exercise | Q 39 | Page 129

Is there a gravitational attraction between you and the book? Explain.

Exercise | Q 40 | Page 129

Does the force of the earth's gravitation affect the motion of the moon? Explain your answer with reasons.

Exercise | Q 41 | Page 129

Differentiate between gravitational mass and inertial mass.

Exercise | Q 42.1 | Page 129

State Newton's law of gravitation. What is the difference between:
Gravity and gravitation

Exercise | Q 42.2 | Page 129

State Newton's law of gravitation. What is the difference between:
g and G?

Exercise | Q 43 | Page 129

An apple falls towards the earth due to its gravitational force. The apple also attracts the earth with the same force. Why do we not see the earth rising towards the apple? Explain.

Exercise | Q 44 | Page 129

Show that gravity decreases at higher altitudes.

Exercise | Q 45.1 | Page 129

In the below figure, a block of weight 20 N is hanging from a rigid support by a string. Find:
The force exerted by block on the string.

Exercise | Q 45.2 | Page 129

In the below figure, a block of weight 20 N is hanging from a rigid support by a string. Find:
The force exerted by string on the block.

Exercise | Q 46 | Page 129

A force of 4 N gives a mass m1 an acceleration of 8 ms-2 and a mass m2 an acceleration of 20 ms-2. What would be the acceleration if the same force acts on both the masses tied together?

Exercise | Q 47 | Page 130

The speed-time graph of a body having a mass of 100 g moving along a straight line path is shown here. Find the force acting on the body.

Exercise | Q 48 | Page 130

A force of 0.9 N acting on a body increases its velocity from 5 ms-1 to 8 ms-1 in 2 s. Calculate the mass of the body.

Exercise | Q 49 | Page 130

The distance-time values for an object moving along straight line are given below:

 Time (s) Distance (m) 0 0 1 1 2 8 3 27

Exercise | Q 50 | Page 130

What do you mean by an impulsive force?

Exercise | Q 51 | Page 130

For how long should a force of 100 N act on a body of mass 20 kg so that it acquires a velocity of 100 ms-1?

Exercise | Q 52 | Page 130

Write the SI unit of retardation.

Exercise | Q 53 | Page 130

What is the relationship between force and acceleration?

Exercise | Q 54 | Page 130

State Newton's second law of motion.
A body of mass 400 g is resting on a frictionless table. Find the acceleration of the body when acted upon by a force of 0.02 N.

Exercise | Q 55 | Page 130

What do you mean by linear momentum of a body? A force causes an acceleration of 10 ms-2 in a body of mass 1 kg. What acceleration will be caused by the same force in a body of mass 4 kg?

Exercise | Q 56 | Page 130

Two bodies P and Q, of same masses m and 2m are moving with velocities 2 v and v respectively. Compare their
(i) Inertia, (ii) Momentum, and (iii) The force required to stop them in the same time.

Exercise | Q 57 | Page 130

Show that the rate of change of momentum = mass × acceleration. Under what condition does this relation hold?

Exercise | Q 58 | Page 130

What do you mean by the conservation of momentum? Briefly, explain the collision between two bodies and the conservation of momentum.

Exercise | Q 59 | Page 130

State Newton's third law of motion. Give an experimental demonstration of Newton's third law.

Exercise | Q 60 | Page 130

A force acts for 0.1 s on a body of mass 2.0 kg initially at rest. The force is then withdrawn and the body moves with a velocity of 2 ms-1. Find the average force applied by the player

Exercise | Q 61 | Page 130

A cricket ball of mass 500 g moving at a speed of 30 ms 1 is brought to rest by a player in 0.03 s. Find the average force applied by the player.

Exercise | Q 62 | Page 130

A force acts for 0.1 s on a body of mass 3.2 kg initially at rest. The force then ceases to act and the body moves through 3 m in the next one second. Calculate the magnitude of force.

Exercise | Q 63 | Page 130

Below Figure shows the velocity-time graph of a particle of mass 200 g moving in a stra ight line. Calculate the force acting on the particle.

Exercise | Q 64.1 | Page 131

A force of 10 N acts on a body of mass 2 kg for 3 s, initially at rest. Calculate:
The velocity acquired by the body.

Exercise | Q 64.2 | Page 131

A force of 10 N acts on a body of mass 2 kg for 3 s, initially at rest. Calculate:
Change in momentum of the body.

Exercise | Q 65.1 | Page 131

Use Newton's second law to explain the following:
We always prefer to land on sand instead of hard floor while taking a high jump.

Exercise | Q 65.2 | Page 131

Use Newton's second law to explain the following:
While catching a fast moving ball, we always pull our hands backwards.

Exercise | Q 66.1 | Page 131

A stone is dropped from a cliff 98 m high.
How long will it take to fall to the foot of the cliff?

Exercise | Q 66.2 | Page 131

A stone is dropped from a cliff 98 m high.
What will be its speed when it strikes the ground?

Exercise | Q 67 | Page 131

A stone is thrown vertically upward with a velocity of 9.8 m/s. When will it reach the ground?

Exercise | Q 68 | Page 131

A ball is thrown vertically downward with an initial velocity of 10 m/s. What is its speed 1 s later and 2 s later?

Exercise | Q 69 | Page 131

A ball is thrown upward and reaches a maximum height of 19.6 m. Find its initial speed?

Exercise | Q 70 | Page 131

A stone is dropped from a tower 98 m high. With what speed should a second stone be thrown 1 s later so that both hit the ground at the same time?

Exercise

## Frank solutions for Class 9 Physics ICSE chapter 3 - Laws of Motion

Frank solutions for Class 9 Physics ICSE chapter 3 (Laws of Motion) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CISCE Class 9 Physics ICSE solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Class 9 Physics ICSE chapter 3 Laws of Motion are cgs and SI Units of Force and Their Relation with Gravitational Units, General Properties of Non-contact Forces, Newton'S First Law of Motion, Definitions of Inertia and Force from First Law, Newton’s Second Law of Motion, Newton's Third Law of Motion, Universal Law of Gravitation, Free Fall, Weight as Force of Gravity, Gravitational Units of Force, Concept of Non-contact Forces, Concept of Weight.

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