Lakhmir Singh Solutions for Class 9th Physics Chapter 1: Motion

The chapter focuses primarily on the movement of the body, i.e. motion, and understanding various aspects of motion. For example, the length travelled by the body while moving is called distance, a scalar quantity. While the shortest distance travelled by the body from an initial point to a final point is termed as displacement of the body, which is a vector quantity. The chapter further explains two types of motion:

• Uniform Motion
• Non-Uniform

The speed of the moving body is a scalar quantity which gives us an idea of how fast or slow the body is moving, and its SI unit is m/sec. The average speed of a body is the total distance travelled divided by the total time taken, and if the body travels an equal distance in an equal interval of time, it is said to be moving at a uniform speed.

The chapter further explains the concept of velocity and rate of change of velocity, i.e. acceleration. Velocity can be expressed as total displacement divided by the total time taken. Its SI unit is the same as speed, but it is a vector quantity. A body has uniform velocity if it moves an equal distance in an equal interval of time in a specific direction. Acceleration can be of the following types:

• Uniform Acceleration
• Non-Uniform Acceleration
  1. Retardation/Negative Acceleration/ Deceleration: When the body's velocity decreases, it is called retardation, which is acceleration with a negative sign.

The chapter consists of three equations of motion and their derivations to provide a deep insight into uniformly accelerated motion. Further, the following types of graphs and derivation of equations of motions using graphs are included to understand motion in two dimensions:

• Distance-Time Graph
• Speed-Time Graph
  1. When speed remains constant
  2. When speed changes at a uniform rate
  3. When the initial speed of the body is anything but zero.
  4. When speed changes at a non-uniform rate

The chapter concludes with circular motion, i.e. motion of an object in a circle. When the body's movement is circular with constant speed, it is said to have uniform circular motion. Example:- Artificial satellites are moving around the Earth, a cyclist on a circular track or tip of the second hand of the watch.

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Key Features of Aakash Lakhmir Singh Solutions for Class 9th Physics Chapter 1: Motion:

• The chapter lays the basis of physics, and the solutions by Aakash lay the foundation in a very easy language.
• The solutions make sure that the students have every answer to the questions asked.