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

Laws of Motion Exe-3A Contact and Non-contact Forces Short and Long Answer Type for Class-9 ICSE Concise Physics. There is the solutions of Short and Long 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-3A Contact and Non-contact Forces 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 – 3A Contact and Non-contact Forces Topics Solution of Exe-3(A) Short and Long Answer Type Academic Session 2023-2024

### Exe-3A Contact and Non-contact Forces Short Answer Type

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

Page 65

#### Question 1. Explain giving two examples each of :

(a) Contact forces

(b) Non – contact forces

(a) The forces which act on bodies when they are in physical contact are called contact forces.

Example: frictional force and force exerted on two bodies during collision.

(b) The forces experienced by bodies even without being physically touched are called non-contact forces.

Example: Gravitational force and Electrostatic force.

#### Question 2. State the effects of a force applied on

(i) A non-rigid, and

(ii) A rigid body.

How does the effect of the force differ in the two cases?

A force when applied on a non-rigid body changes the inter-spacing between its constituent particles and therefore causes a change in its dimensions and can also produce motion in it.

On the other hand, a force when applied on a rigid body, does not change the inter-spacing between its constituent particles and therefore it does not change the dimensions of the body but causes motion in it.

#### Question 3. What is the frictional force ? Draw a neat labelled diagram showing a frictional force acting on a body.

Frictional force is the force generated by two surfaces that contact and slide against each other.

#### Question 4. What is a normal reaction force ? Draw a neat labelled diagram showing a normal reaction force acting on a body.

Answer : The normal force is a force that is felt every day. For example, when we place a book on a table, the typical reaction force resists the book from falling through the table, the strength of gravity is drawing the book downward, but the book isn’t falling.

### Exe-3A Contact and Non-contact Forces Long Answer Type

Laws of Motion Exe-3A Short Answer Class-9 ICSE

Page 65

#### Question 1.

(a) A ball is hanging by string from the ceiling of the roof. Draw a neat labelled diagram showing the forces acting on the ball and the string.

(b) A spring is compressed against a rigid wall. Draw a neat and labeled diagram showing the forces acting on the spring.

(c) A wooden block is placed on a table top. Name the forces acting on the block and draw a neat and labelled diagram to show the point of application and direction of these forces.

(a)

(c)

The forces acting on the block are its weight in the downward direction and the normal reaction force due to the table on the upward direction.

—  : End of Laws of Motion Exe-3A Contact and Non-contact Forces Short and Long Answer Type  Solutions :–

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