⬆️ TOP EDUCATION ⬆️
CBSE
CLASS 9 SCIENCE
CHAPTER 8
MOTION
NOTES
Motion
⚫ Motion is the change in position of an object with respect to its surroundings.
⚫It can be described in terms of distance, displacement, speed, velocity, and acceleration.
Distance and Displacement:
⚫Distance is the total path covered by an object during its motion and is a scalar quantity.
⚫ Displacement is the shortest distance between the initial and final positions of an object, taking into account direction, and is a vector quantity.
⚫Displacement can be zero if the object returns to its initial position, whereas the distance covered will not be zero.
Speed and Velocity:
⚫Speed is the distance covered per unit of time and is a scalar quantity.
⚫It is given by the formula: Speed = Distance/Time.
⚫Velocity is the displacement per unit of time and is a vector quantity.
⚫It is given by the formula: Velocity = Displacement/Time.
Types of Motion:
1. Uniform Motion: When an object covers equal distances in equal intervals of time, it is said to be in uniform motion.
2. Non-uniform Motion: When an object covers unequal distances in equal intervals of time, it is said to be in non-uniform motion.
3. Rectilinear Motion: When an object moves along a straight line path, it is said to be in rectilinear motion.
4. Circular Motion: When an object moves in a circular path, it is said to be in circular motion.
5. Periodic Motion: When an object repeats its motion after regular intervals of time, it is said to be in periodic motion.
Acceleration:
⚫ Acceleration is the rate of change of velocity and is a vector quantity.
⚫ It can be calculated using the formula: Acceleration = Change in Velocity/Time.
⚫ Acceleration can be positive (when the velocity increases), negative (when the velocity decreases), or zero (when the velocity remains constant).
Graphical Representation of Motion:
⚫ Distance-time graph: It represents the variation in the distance with respect to time.
⚫ Velocity-time graph: It represents the variation in velocity with respect to time.
⚫ The slope of a distance-time graph gives the speed, while the slope of a velocity-time graph gives the acceleration.
🌟These are some basic notes on Chapter 8: Motion. Make sure to refer to your textbook and class notes for more detailed information and examples.
