Motion Lesson For Class 9th Physics

What is Motion

  • In everyday life, we see some objects at rest and others in motion.

  • Birds fly, fish swim, blood flows through veins and arteries and cars move.
  • Atoms, molecules, planets, stars, and galaxies are all in motion.
  • We often perceive an object to be in motion when its position changes with time.
  • However, there are situations where the motion is inferred through indirect evidence.
  • For example, we infer the motion of air by observing the movement of dust and the movement of leaves and branches of trees.
  • What causes the phenomena of sunrise, sunset, and changing of seasons?
  • Is it due to the motion of the earth?
  • If it is true, why don’t we directly perceive the motion of the earth?
  • An object may appear to be moving for one person and stationery for some other.
  • For the passengers in a moving bus, the roadside trees appear to be moving backward.
  • A person standing on the roadside perceives the bus along with the passengers as moving.
  • However, a passenger inside the bus sees his fellow passengers be at rest.
  • What do these observations indicate? Most motions are complex.
  • Some objects may move in a straight line, others may take a circular path.
  • Some may rotate and a few others may vibrate.
  • There may be situations involving a combination of these.
  • In this chapter, we shall first learn to describe the motion of objects along a straight line.
  • We shall also learn to express such motions through simple equations and graphs. Later, we shall discuss ways of describing circular motion.

After This Course, you will learn

  • Movement of a body(or object)
  • Distance traveled and displacement
  • Uniform motion and non-uniform motion
  • Speed
  • Average speed
  • Acceleration
  • Speed-Time Graph
  • Deriving Equations of motion by graphical method
  • Numerical based on equations of motion
  • Uniform Circular motion
  • Motions of satellites around the earth
  • Calculating the speed of a body moving in a circular path.
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