CBSE Class 9th Science 9 – Force and laws of motion MCQs

Inertia is the property of a body, by virtue of which the body is unable to change its ____ by itself.

Correct! Wrong!

Inertia is the property of a body, by virtue of which the body is unable to change by itself, the state of rest, direction and uniform motion.

The force acting between two charged particles is known as ____.

Correct! Wrong!

The force acting between two charged particles is known as electric force.

____ is the branch of mechanics which deals with the study of the objects in equilibrium that are under the action of external forces.____ is the branch of mechanics which deals with the study of the objects in equilibrium that are under the action of external forces.

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Statics is the branch of mechanics which deals with the study of the objects in equilibrium that are under the action of external forces.

The weight of a body ____.

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The weight of a body is the force with which it is attracted by the earth.

When a person walks over a rough surface, direction of friction is along the direction of motion of the person.

Correct! Wrong!

When a person walks over a rough surface, direction of friction is along the direction of motion of the person.

Which of the following quantities is a vector?

Correct! Wrong!

Force is a vector quantity as it has both magnitude as well as direction.

Before taking a long jump, an athlete runs for a certain distance, this is an example of ____.

Correct! Wrong!

Before taking a long jump, an athlete runs for a certain distance and then leaps. Athlete uses inertia of motion to complete the jump. Hence, it is an example of inertia of motion.

Newton's first law of motion is also known as the law of inertia.

Correct! Wrong!

Newton's first law of motion states that every body remains in its state of rest or of uniform motion unless it is compelled by an external force, acting on it which is also known as the law of inertia.

Friction between any two objects is caused due to the interlocking of irregularities present on the surface that are in contact.

Correct! Wrong!

Friction between any two objects is caused due to the interlocking of irregularities present on the surface that are in contact.

Which of the following forces is the weakest force in nature?

Correct! Wrong!

Gravitational force is the weakest force in nature.

The force is defined as a physical cause, which can change the speed or direction of motion or both of a body.

Correct! Wrong!

Force is defined as a physical cause, which can change the speed or the direction of motion or both of a body.

Force is a vector quantity.

Correct! Wrong!

Force is a physical quantity which has both magnitude and direction. Hence, force is a vector quantity.

When a berry tree is shaken vigorously and suddenly, the fruits are detached from the branches due to inertia of motion.

Correct! Wrong!

When a berry tree is shaken vigorously and suddenly, the fruits are detached from the branches due to inertia of rest.

In the CGS system, the unit of force is ____.

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In the CGS system, the unit of force is dyne.

The inertia of a body depends upon ____ of the body.

Correct! Wrong!

The inertia of a body depends upon mass of the body.

Force can be completely described alone by its magnitude, hence it is a scalar quantity.

Correct! Wrong!

Force is a vector quantity. Hence, it has both magnitude as well as direction.

The force acting between two mass particles is known as magnetic force.

Correct! Wrong!

The force acting between two mass particles is known as gravitational force.

When a car suddenly takes a turn, the passengers are thrown in the outward direction. This is an example of inertia of ____.

Correct! Wrong!

When a car suddenly takes a turn, the passengers are thrown in the outward direction due to inertia of direction.

The ____ is a measure of inertia of a body in linear motion.

Correct! Wrong!

The mass is the measure of inertia of a body in linear motion.

The inertia of the body is proportional to its mass.

Correct! Wrong!

The inertia of the body is proportional to its mass.

For a body to keep moving with uniform velocity, an external force is required .

Correct! Wrong!

Due to inertia of motion, the body continues moving with uniform velocity without any external force.

A boy standing in a bus falls backward, when the bus accelerates suddenly from rest. This is due to ____.

Correct! Wrong!

When the bus accelerates suddenly from rest the lower part of the body that is in contact with the bus moves forward, but the upper part continuous to be in its state of rest, due inertia of rest. Hence, the person falls back.

An object will continue moving uniformly as long as the resultant force on it is ____.

Correct! Wrong!

According to the principle of inertia, the object continues in its state of motion unless a force acts on it.

When a unpowered bicycle travels on a smooth surface its speed ____.

Correct! Wrong!

According to Newton's first law of motion, external force is required to change the state of the body. As there is no external force on the bicycle, it moves with constant speed

Which of the following law of Newton gives us the qualitative study of force?

Correct! Wrong!

Newton’s first law gives the qualitative study of force which states that everybody remains in its state of rest or of uniform motion, unless it is compelled by an external force.

A person standing in a local train falls forward, when the brakes are applied suddenly. This is due to ____.

Correct! Wrong!

When the brakes are applied the lower part of the body that is in contact with train comes to rest, but the upper part continuous to be in its state of motion, due inertia of motion. Hence, the person falls forward.

Which of the following law explains the concept of inertia?

Correct! Wrong!

Newton's first law of motion states that everybody remains in its state of rest or of uniform unless it is compelled by an external force, acting on it which explains the concept of inertia.

An unbalanced force acting on an object brings it in motion.

Correct! Wrong!

An unbalanced force acting on an object brings it in motion.

Which of the following represents the SI unit of force?

Correct! Wrong!

The SI unit of force is newton, N.

Unbalanced forces acting on a body can change the shape of the body.

Correct! Wrong!

Balanced forces acting on a body change the shape of the body.

CBSE Class 9th Science 9 - Force and laws of motion MCQs
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