Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Class 9 MCQ

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Class 9 MCQ

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25 Questions MCQ Test Science Class 9 - Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion for Class 9 2024 is part of Science Class 9 preparation. The Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion questions and answers have been prepared according to the Class 9 exam syllabus.The Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion MCQs are made for Class 9 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion below.
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Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 1

An external influence which changes or tends to change the state of rest or uniform motion of body or its dimensions is called :

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 1

Force is a phenomenon which is responsible for the change in state or shape or size of a body either from rest to motion or motion to rest.

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 2

Equal and opposite forces acting on a body which do not change its state of rest or uniform motion are called:

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 2

The correct option is C.
Balanced force:Forces acting on an object which does not change the state of rest or of uniform motion of it are called balanced forces. Unbalanced force:The resultant of two opposite forces acts on an object and brings it in motion. These opposite forces are called unbalanced forces.

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 3

The unequal and opposite forces acting on a body, which change its state of rest or uniform motion are called:

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 3

Explanation :- When two forces of unequal magnitudes act in opposite directions on an object simultaneously then the object moves in the direction of the force with larger magnitude forces. These forces acting on the object are known as unbalanced forces.

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 4

Force of friction always acts in the direction:

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 5

When balanced forces act on a body, the body:

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 5

According to the law of inertia or Newton's first law of motion, a body in state of rest or of uniform motion remains in state of rest or of uniform motion unless it is acted upon by an external force. Hence a body in uniform motion required no force to keep them in uniform motion.

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 6

When unbalanced forces act on a body, the body:

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 6

The Second Law of Motion states that if an unbalanced force acts on a body, that body will experience acceleration ( or deceleration), that is, a change of speed.

One can say that a body at rest is considered to have zero speed, ( a constant speed). So any force that causes a body to move is an unbalanced force. Also, any force, such as friction, or gravity, that causes a body to slow down or speed up, is an unbalanced force.

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 7

If no external force acts on a body, it will :

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 8

If a body is allowed ti freely fall from a height, its speed increases continuously. It is because:

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 8

The gravitational force for a falling object is along the direction of motion. Hence, its speed increases continuously till  it touches the ground.

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 9

A force of magnitude' F' acts on a body of mass 'm'. The acceleration of the body depends upon:

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 9

F = m × a
Where, F = force
m = mass
a = acceleration

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 10

Force remaining constant, if the mass of body increases, its acceleration is likely to :

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 11

A force F produces an acceleration 'a' in a body. The same force produces and acceleration 4a in another
body. The mass of other body is :

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 12

When a running motorbike accelerates suddenly, the pillion rider has a tendency to fall backward. This is an example of:

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 12

Law of Inertia or First law of motion.
As the body tends to be in its original state when the horse suddenly stops, The lower part of the rider stops with it but the upper part remains in motion. So, the rider falls forward.

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 13

A force F acts on a stationary body for the time t. The distance covered by the body 'S' will be proportional to:

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 13
S=ut+1/2at^2 Since the mass is constant, and i guess you dont mean above to be dealt in relativistic speed, and a constant force is applied then we will have constant acceleration. So distance covered will be only dependent on elapsed time t.So s ∝ t^2
Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 14

The impact which a body can produce due to the combined effect of mass and velocity is called:

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 14

Mass ad velocity both are considered to be quantities which defines motion.

The combination of both is called quantity of motion. It is momentum.

P = mv

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 15

The SI unit of momentum is :

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 15

If we consider the situation when force is equivalent to the rate of change of momentum. I.e Force = (change in momentum)(time interval)
then, change in momentum = Force * (time interval).
Therefore, the unit for momentum can be Newton - second (Ns)

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 16

The tendency of a body to continue in its state of rest or uniform motion, even on the application of external force is called:

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 16

The intrinsic property of material body which resists a change in its state of rest or of uniform
motion along a straight line is called inertia.
Inertia is a natural tendency of the body. Mass is taken as a quantitative measure of inertia of a
material body. The larger the mass of a body the greater the difficulty in bringing about a change in its
state of motion, i.e. the mass is a measure of inertia.

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 17

A body will continue in its state of rest or uniform motion in a straight line, unless acted by some external force. The statement represents :

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 17
Body is in the motion it tends to be in motion and when a body is in the rest it tends to be in rest unless and external force is not applied on it.
Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 18

The magnitude of inertia of a body is determined by its:

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 19

Momentum is a:

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 19

Momentum is a vector quantity. For a particle with mass, the momentum equals mass times velocity, and velocity is a vector quantity while mass is a scalar quantity. A scalar multiplied by a vector is a vector. A moving body would be a particle with a mass.

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 20

A body P has mass 2 m and velocity 5 v. Another body Q has mass 8 m and velocity 1.25 v. The ratio of momentum of P and Q is :

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 20
Momentum = mass x velocity
Therefore in first case momentum = 2m x 5v = 10mv
​Therefore in second case momentum = 8m x 1.25v = 10mv
​Thus in both the cases momentum is the same, so, Ratio is 1:1
Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 21

The magnitude of a physical quantity is 8.5 Ns. The physical quantity is :

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 21
The newton second (also newton-second, symbol N s or N·s) is the derived SI unit of impulse. It is dimensionally equivalent to the momentum unit kilogram metre per second (kg·m/s). One newton second corresponds to a one-newton force applied for one second. Derivation- p=mv =kg×m/s =kgm/s×s/s =kgm/s^2×s =N×s
Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 22

There is a rubber ball and a stone ball of same size. If both balls are at rest:

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 23

When we vigorously a shake branch of a tree, some leaves get detached. It is due to the:

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 24

When the driver of a fast moving car suddenly applies brakes, the passengers in the car:

Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 25

Which is the incorrect statement? A spaceship continues moving in space with uniform speed because:

Detailed Solution for Lakhmir Singh & Manjit Kaur Test: Forces & Laws of Motion - Question 25
A spaceship continues moving in space with uniform speed because no force of gravitation acts on it but not it's mass is zero in space and everything in the space appear to be floating that is why the astronauts also appear to float in space but their mass is not zero actually.

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