# Laws of Motion Exe-3B Very Short Answer Physics Class-9 ICSE Selina Publishers

Laws of Motion Exe-3B Newton’s First Law Inertia Very Short Answer Type for Class-9 ICSE Concise Physics. There is the solutions of Very short Answer type Questions of your latest textbook which is applicable in 2023-24 academic sessionVisit official Website CISCE for detail information about ICSE Board Class-9.

## Laws of Motion Exe-3B Newton’s First Law Inertia Very Short Answer

(ICSE Class – 9 Physics Concise Selina Publishers)

 Board ICSE Class 9 Subject Physics Writer / Publication Concise selina Publishers Chapter-3 Laws of Motion Exe – 3B Newton’s First Law Inertia Topics Solution of Exe-3(B) Very Short Answer Type Academic Session 2023-2024

### Exe-3B Newton’s First Law Inertia Very Short Answer Type

Ch-3 Laws of Motion Physics Class-9 ICSE Concise

Page 69

#### Question 1. Name the physical quantity that causes motion in a body.

Force causes motion in a body

#### Question 2. Is force needed to keep a moving body in motion?

Force is not needed to keep a moving body in motion.

#### Question 3. A ball is moving on a perfectly smooth horizontal surface. If no force is applied on it, then will its speed decrease, increase or remain unchanged?

In absence of any external force, its speed shall remain unchanged.

#### Question 4. What is Galileo’s law of inertia?

Galileo’s law of inertia states that a body continues to be in its state of rest or of uniform motion unless an external force is applied on it.

#### Question 5. State Newton’s first law of motion.

According to Newton’s first law of motion, if a body is in a state of rest, it will remain in the state of rest, and if the body is in the state of motion, it will remain moving in the same direction with the same speed unless an external force is applied on it.

#### Question 6. Give the qualitative definition of force based on Newton’s first law of motion.

Force is that external cause which can move a stationary object or which can stop a moving object.

#### Question 7. Name the factor on which the inertia of a body depends and state how does it depend on the factor stated you.

Inertia of a body depends on its mass. Inertia is directly proportional to mass, i.e. greater the mass of a body, greater is its inertia

(Laws of Motion Exe-3B Very Short Class-9 ICSE)

#### Question 8. Name the two kinds of inertia.

Answer: Two kinds of inertia are as listed below:

(i) Inertia of rest.

(ii) Inertia of motion.

#### Question 9. Give oneexample of each of the following :

(a) Inertia of rest, and

(b) Inertia of motion.

Examples of inertia of rest: A coin placed on top of a card remains in place when the card is slightly and quickly jerked horizontally.

Example of inertia of motion: A ball thrown vertically upwards by a person in a moving train comes back to his hand.

#### Question 10. An aeroplane is moving uniformly at a constant height under the action of two forces (i) Upward force (lift) and (ii) Downward force (weight). What is the net force on the aeroplane?

The net force on the airplane is zero or the upward force is equal to the downward force.

—  : End of Laws of Motion Exe-3B Newton’s First Law Inertia Very Short Answer Type  Solutions :–

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