Class 9th
PHYSICS
MOTION
Motion
An object is said to be in the state of motion if it changes its position with respect to time and its surroundings.
Rest
An object is said to be in the state of rest if it does not change its position with respect to time and its surroundings.
Scalar Quantities
Physical quantities having magnitude but no direction are called scalar quantities. e.g., distance, speed.
Vector Quantities
Physical quantities having both magnitude and direction are called vector quantities. e.g., displacement, velocity.
Distance
• The actual path or length travelled by an object during its journey from its initial position to its final
position is called the distance.
• Distance is a scalar quantity.
• Distance can never be negative.
• S.I Unit is “metre”
Displacement
• It is the shortest distance between the initial and final position of an object.
• Displacement is a vector quantity.
• Displacement can be positive, negative or zero.
• S.I Unit is “metre”.
Uniform Motion
When a body travels equal distance in equal interval of time, then the motion is said to be uniform motion.
Non uniform motion
When a body travels equal distance in an unequal interval of time or unequal distance in equal interval of time, then
the motion is said to be non uniform motion.
Speed
• The measurement of distance travelled by a body per unit time is called speed.
• Speed = Distance travelled / Time taken
• Speed is a scalar quantity.
• S.I Unit is m/s.
Velocity
• It is the speed of a body in a given direction.
• Velocity = Displacement / Time
• Velocity is a vector quantity.
• S.I unit is m/s.
Average Speed
• The total distance travelled divided by the total time taken is called average speed.
• Average speed = Total distance travelled / Total time taken
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PHYSICS
MOTION
Motion
An object is said to be in the state of motion if it changes its position with respect to time and its surroundings.
Rest
An object is said to be in the state of rest if it does not change its position with respect to time and its surroundings.
Scalar Quantities
Physical quantities having magnitude but no direction are called scalar quantities. e.g., distance, speed.
Vector Quantities
Physical quantities having both magnitude and direction are called vector quantities. e.g., displacement, velocity.
Distance
• The actual path or length travelled by an object during its journey from its initial position to its final
position is called the distance.
• Distance is a scalar quantity.
• Distance can never be negative.
• S.I Unit is “metre”
Displacement
• It is the shortest distance between the initial and final position of an object.
• Displacement is a vector quantity.
• Displacement can be positive, negative or zero.
• S.I Unit is “metre”.
Uniform Motion
When a body travels equal distance in equal interval of time, then the motion is said to be uniform motion.
Non uniform motion
When a body travels equal distance in an unequal interval of time or unequal distance in equal interval of time, then
the motion is said to be non uniform motion.
Speed
• The measurement of distance travelled by a body per unit time is called speed.
• Speed = Distance travelled / Time taken
• Speed is a scalar quantity.
• S.I Unit is m/s.
Velocity
• It is the speed of a body in a given direction.
• Velocity = Displacement / Time
• Velocity is a vector quantity.
• S.I unit is m/s.
Average Speed
• The total distance travelled divided by the total time taken is called average speed.
• Average speed = Total distance travelled / Total time taken
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