Kinematics

Kinematics

Basic Concepts

• Kinematics is the study of objects in motion, dealing with displacement, velocity, and acceleration.
• Displacement refers to an object’s overall change in position.
• Velocity is the rate of change of displacement.
• Acceleration is the rate of change of velocity.

Types of Motion

• Uniform motion signifies movement in a straight line at a constant speed.
• Non-uniform motion implies movement where speed changes.

Equations of Motion

• First equation: Final velocity (v) is initial velocity (u) plus acceleration (a) times time (t) or v = u + at.
• Second equation: Displacement (s) is the product of initial velocity and time plus half of the acceleration times square of time or s = ut + 1/2at².
• Third equation: The square of final velocity equals the square of initial velocity plus double the product of acceleration and displacement or v² = u² + 2as.

Graphical Representation

• Velocity vs time graph: The gradient gives acceleration and the area under the graph gives the displacement.
• Displacement vs time graph: The gradient gives the velocity.

Freely Falling Bodies

• Remember for objects falling freely under gravity close to the earth’s surface, the acceleration (a) is taken as g = 9.8 m/s² downwards. If upwards motion is taken to be positive, then g = -9.8 m/s².

Relative Motion

• Relative velocity is the velocity of one body with respect to another.
• It is crucial to understand how to calculate relative velocity in same or opposite directions.