## 20 Questions

What is a force that always opposes the motion of objects called?

Frictional force

What is the SI unit of force?

Newton

When are forces said to be balanced forces?

When they nullify each other and their resultant force is zero

What does a force consist of?

Both magnitude and direction

What does a force do to an object it acts upon?

Produces acceleration

What is the product of mass and velocity known as?

Momentum

In the formula F = ma, what does 'F' represent?

Force

What is the SI unit of momentum?

kg m/s

What is the natural tendency of an object to resist a change in its state of rest or of uniform motion called?

Inertia

According to the law of conservation of momentum, what happens to the sum of momenta of two objects before and after collision?

It remains constant

What is the SI unit of momentum?

kg m/s

According to the second law of motion, what is the relationship between the rate of change of momentum and the applied unbalanced force?

Directly proportional

What is the natural tendency of an object to resist a change in its state of rest or of uniform motion called?

Inertia

What is the formula for momentum?

$mv$

In the law of conservation of momentum, what happens to the total momentum of a system if the external force on the system is zero?

Remains constant

What is the SI unit of force?

Newton

What is the natural tendency of an object to resist a change in its state of rest or of uniform motion called?

Inertia

What is the product of mass and acceleration known as?

Force

When are forces said to be balanced forces?

When their resultant force is zero

What is the force that always opposes the motion of objects called?

Friction

## Study Notes

### Forces and Motion

- A force that always opposes the motion of objects is called friction.
- The SI unit of force is the Newton (N).

### Balanced Forces

- Forces are said to be balanced forces when they result in no net force or acceleration on an object.

### Force and Momentum

- A force consists of a push or pull that causes an object to change its motion.
- A force acting on an object causes it to change its velocity, i.e., accelerate.
- The product of mass and velocity is known as momentum.

### Formulae

- The formula F = ma represents force (F), mass (m), and acceleration (a).
- In the formula F = ma, 'F' represents force.
- The formula for momentum is p = mv, where p is momentum, m is mass, and v is velocity.

### Momentum and Conservation

- The natural tendency of an object to resist a change in its state of rest or of uniform motion is called inertia.
- According to the law of conservation of momentum, the sum of momenta of two objects before and after collision remains the same.
- The SI unit of momentum is the kilogram-meter per second (kg·m/s).
- If the external force on a system is zero, the total momentum of the system remains constant.

### Second Law of Motion

- According to the second law of motion, the rate of change of momentum is proportional to the applied unbalanced force.

Access summary and revision notes for Class 9 Science Chapter 9 on Force and Laws of Motion. These CBSE notes include key points, revision notes, images, and diagrams for comprehensive understanding of the chapter. Ideal for students using NCERT Textbook for Science.

## Make Your Own Quizzes and Flashcards

Convert your notes into interactive study material.

Get started for free