Notes For Class 9 Science Chapter 1 Laws of motion | Laws of motion notes for class 9 Maharashtra board

Notes For Class 9 Science Chapter 1 Law's of motion | Law's of motion notes for class 9 Maharashtra board 

Motion :-

The position of an object changes with respect to surrounding called as object are is in motion.

e.g. 

1) A flying bird.

2)Throwing a ball..

3)motion of swing. 

4) planetary motion.

5) A moving car. 

Rest :-

The position of an motion does not change respect to surrounding is called as object with is at rest.

e.g. 

1) Door 

2) benches in classroom.

3) School, houses

4) mount everest 

5) Switch off fan

Distance :-

The actual length travelled by object is called as distance.

e.g.

The car travels the west direction for 5 kilometer and takes a turn to travel south direction for another 8 kilometers , the total distance travelled by car shall be 13 kilometers.

• SI unit is meter (m)
• It is a scalar quantity 

Displacement :-

The minimum distance travelled by an object are called as displacement.

• SI unit is meter (m)
• It is a vector quantity 

Notes For Class 9 Science Chapter 1 Law's of motion | Law's of motion notes for class 9 Maharashtra board 

# Physical quality 

  Physical quantity is use for measurement.

Types of physical quantity

• Scalar quantity
• Vector quantity 

Scalar quantity :-

      A physical quantity has only magnitude.

E.g. distance, speed, time etc.

Vector quantity :-

     A Physical quantity have magnitude as well as direction.

 E.g. velocity, displacement, force, pressure etc.

Question : the path of length travel by 'A' from 'B' house is 10 km and he is come back again it's original position. Find the distance and displacement.

Ans.

  

A -------<----------------------->------ B 

     10 km >                   < 10 km

1. Distance = 10 km + 10 km = 20 km 

2. Displacement = zero

Speed :-

     The distance traveled by body per unit time is called as speed.

Speed = Distance travelled / Time taken

Question : the distance traveled by a car in 20 seconds is 400 meter find its speed.

Ans.

Formula -  Speed = Distance travel / time taken

 :.  400 / 20 = 20 m/s

• SI unit is (m/s).
• CGS unit is (cm/s).
• It is a vector quantity.

Velocity :-

The rate of alter of displacement per unit time is called velocity.

Velocity = displacement / time 

• SI unit is (m/s ).
• CGS unit is (cm/s).
• It is a vector quantity.

Notes For Class 9 Science Chapter 1 Law's of motion | Law's of motion notes for class 9 Maharashtra board 

What are the notes of the first law of motion class 9th?

The first law of motion states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force