Unlock the Secrets of Motion with Future Classes' CBSE Class 9 Science Course
The CBSE Class 9 Science notes on Motion offer a comprehensive overview of the concepts, theories and topics related to this subject. Students can learn about the different types of motion, including linear and circular, and understand the factors that affect motion, such as force, mass, speed and acceleration. They can also explore the laws of motion, including Newton's three laws, and learn about the different types of energy, such as the kinetic and potential energy. With the help of these notes, students can gain a better understanding of the concepts of motion and be better equipped to solve problems related to it.
At Future Classes, we are dedicated to helping students achieve academic success. That's why we offer a variety of study resources, including our short notes on CBSE class 9 science chapter motion. Written by Anurag, our notes are easy to read and provide a comprehensive overview of the subject. Download your copy today and start studying smarter!
MOTION
Rest:
A body is said to be in a state of rest when its position does not change with respect to a reference point.
Motion:
A body is said to be in a state of motion when its position change continuously with reference to a point.
Scalar quantity:
It is the physical quantity having magnitude but no direction. Example -distance, speed.
Vector quantity:
It is the physical quantity having both magnitude and direction. Example - displacement, velocity.
Unit system
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M.K.S. system (S.I. system) – meter, kilogram, second
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C.G.S. system – centimeter, gram, second
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S.I. system – International system of unit
Distance
The actual path of length traveled by an object during its journey from its initial position to its final position is called the distance.
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Distance is a scalar quantity.
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It remains positive, can’t be zero or negative.
Displacement
The shortest length between the initial point and far point of an object.
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It is a vector quantity.
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It can be positive (+ve), negative (-ve), or zero.
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Uniform Motion:
When a body travels an equal distance in an equal interval of time, then the motion is said to be uniform motion.
Non-uniform Motion:
In this type of motion, the body will travel unequal distances in equal intervals of time.
Speed:
The distance traveled by a body per unit of time is called speed.
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SI unit is m/s (meter/second)
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For non-uniform motion
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Velocity:
It is the speed of a body in a given direction.
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SI unit of velocity is m/s
Velocity is a vector quantity.
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For non-uniform motion
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For uniformly changing velocity
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Acceleration:
Acceleration is seen in non-uniform motion and it can be defined as the rate of change of velocity with time.
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Where, v = final velocity, u = initial velocity
S I unit is meter/second2
Retardation/Deceleration
Deceleration is seen in non-uniform motion during a decrease in velocity with time. It has the same definition as acceleration. (-a)
Graphical Representation of motion
Distance-time graph of an object moving with uniform speed
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Distance-time graph for a car moving with non-uniform speed
Velocity-time graph for uniform motion of a car
Velocity-time graph for a car moving with uniform accelerations.
Velocity-time graphs of an object in nonuniformly accelerated motion.
Equation of Motion (For Uniformly Accelerated Motion)
Graphical Derivation:
First Equation
Suppose a body has initial velocity ‘u’ (i.e., velocity at time t = 0 sec.) at point ‘A’, and this velocity changes to ‘v’ at point ‘B’ in ‘t’ sec. i.e., final velocity will be ‘v’.
Second Equation
Third Equation
Uniform Circular Motion
In such a motion the speed may be the same throughout the motion but its velocity (which is tangential) is different at every point of its motion. Thus, uniform circular motion is an accelerated motion.
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Some units
