Chapter 1, Motion for class 9th

1. CHAPTER-1: MOTION
Presented by: Hraday Narayan Pandey

2. CONTENTS
1. Rest and Motion
2. Types of motion
3. Terms used to define motion
4. Various graphs related to motion
5. Equations of motion

3. REST AND MOTION
 Rest: An object is said to be at rest if it does not
changes its position with time.
 Motion: An object is said to be in motion if it
changes its position continuously with time.

4. TYPES OF MOTION
1. According to state of motion
1. Uniform Motion: A body is said to be in state of uniform
motion if it travels equal distances in equal intervals of
time.
2. Non-uniform Motion: A body is said to be in state of
non-uniform motion if it travels unequal distances in
equal intervals of time.

5. TERMS USED TO DEFINE MOTION
1. Distance and Displacement
2. Speed and velocity
3. Acceleration

6. 1. Distance: The total length of the path covered by
an object from its initial position to its final position
is called distance.
 It is a scalar quantity.
 Distance never decreases with time
 It is always positive
2. Displacement: The shortest length of the path
from initial position to final position is called
displacement of an object.
 It is a vector quantity.
 It can be positive, negative and zero.
 Note: In case of motion:
 Distance is always greater than or equal to
displacement.
 i.e. distance ≥ displacement

7.  Speed: The distance travelled by an object per unit
time is called speed of an object.
 It is a scalar quantity.
 Velocity: The displacement of an object per unit
time is called velocity of an object.
 It is a vector quantity.

8.  Acceleration: The rate of change in velocity is
called acceleration.
 It is denoted by ‘a’.
 a=Change in velocity/Time taken
 It is a vector quantity.
 The SI unit of acceleration is ms−2
 When the direction of acceleration is in the direction of motion
of an object, the acceleration is said to be positive
acceleration.
 When the direction of acceleration is opposite to the direction
of motion of an object, the acceleration is said to be negative
acceleration (deceleration or retardation).

9. VARIOUS GRAPH RELATED TO MOTION
 Distance-Time graph:
Slope of s-t graph gives speed
of an object.

11.  Velocity-Time graph:
 Slope of v-t graph gives acceleration.
 Area under the v-t graph gives displacement.

13.  Acceleration-Time graph:
Area of a-t graph gives velocity.

16. EQUATIONS OF MOTION
The motion of an object moving with uniform
acceleration can be described with the help of
three equations called equations of motion.
I. Equation for velocity time relation(1st equation of
motion)
v = u + at
II. Equation for position-time relation(2nd equation of
motion)
s = ut + ½at²
III. Equation for position-velocity relation (3rd
equation of motion)
v² = u² + 2as