# LAWS OF MOTION PDF NOTES |LAWS OF MOTION QUESTION ANSWER

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LAWS OF MOTION PDF NOTES|LAWS OF MOTION QUESTION ANSWER

## 👉What is motion of an object?(LAWS OF MOTION PDF NOTES)

If a body changes its position with respect to its surrounding then body is said to be in a motion and at rest otherwise.

## 👉Give some example that sense motion?

The flight of bird.

Leaves flying through air.

## 👉Give some example that do not sense motion?

Stationery train

A stone lying on hill

## 👉You are travelling in a bus .Is the person sitting next to you in motion?

The person sitting next to me is not in motion, but it is  in motion with respect to person on the road.

## 👉What do you take into consideration to decide if an object is moving or not?

Whether the object changes its position with respect to its surrounding or not decides that an object is moving or not.

## 👉What is distance? Write its SI and CGS unit.

Distance is the lengh of the actual path followed by a body between the points under the consideration. It’s SI unit is metre(m) and CGS unit is centimetre(cm). Distance is the scalar quantity. It means that it has a magnitude only.

## 👉What is displacement? Write its SI and CGS unit.

It is the shortest distance from the initial point to the final point of the moment of body. Its SI unit is metre (m)and CGS unit is centimetre (cm).

It is a vector quantity. It means that it has a magnitude as well as direction.

## 👉What are scalars and vector quantity?

Scalar quantities are those quantities which have magnitude only.

Example: Time ,speed

Vectors qualities are those qualities which have magnitude as  well as direction also

Example: velocity and displacement

## 👉What is speed? Write its SI and CGS unit.

It is a distance covered by a body in unit time.

It’s SI unit is metre per second (m/s) and CGS unit is centimetre per second (cm/s). Speed has a magnitude but no direction. It is a scalar quantity.

## 👉What is velocity? Write its SI and CGS unit.

Velocity is the displacement in unit time. Its SI and CGS units are the same as those of speed. It is a vector quantity. It has a magnitude as well as direction.

## 👉What are uniform motion and non uniform motion?

Uniform motion is the motion in which a body covers equal distances in  very small equal interval of time.

Non uniform motion is the motion in which a body covers unequal distances in equal intervals of time.

## 👉What is acceleration? Write its SI and CGS unit.

Acceleration is the rate of change of velocity with respect to time.

It’s SI unit is metre per second square (m/s2) and CGS unit is centimetre per second square (cm/s2)

## 👉What is positive acceleration ,negative acceleration and zero acceleration?

When the velocity of body increases with time it’s acceleration is positive.

When the velocity of body decreases with time it’s acceleration is negative.

When there is no change in the velocity of a body with time ,it is a zero acceleration.

## 👉What is retardation or deceleration?

Negative acceleration is called retardation or deceleration.

## 👉What is uniform circular motion?

When a body moves in a circular path with uniform speed its motion is said to be uniform circular motion.

## 👉What is Newton’s first law of motion?

An object continues to remain  at rest or in a state of uniform motion along a straight line unless and until external  unbalanced force act on it.

## 👉What is momentum of a body?

Momentum is the product of mass of the body and velocity of the body. It is a vector quantity. It’s SI unit is kilogram metre per second (Kg.m/s)

And CGS unit is gram centimeter per second (g.cm/s)

## 👉What is force?

Force is the product of mass and acceleration of the body. It is a vector quantity. Its SI unit is Newton (N) and CGS unit is dyne.

## 👉What is Newton’s second law of motion?

The rate of change of momentum is proportional to the applied force and the change of momentum occurs in the direction of the force.

## 👉What is Newton’s third law of motion?

Every action force has an equal and opposite reaction force which act simultaneously. i.e equal in magnitude and opposite in direction.

## 👉What is law of conservation of momentum?

When no external force act on two interacting objects, their total momentum remains constant। it does not change