■ Kinematics – Study Notes
1. Introduction
•Kinematics: The branch of physics that deals with the motion of objects without considering the
forces causing them.
•Describes motion in terms of displacement, velocity, acceleration, and time.
2. Basic Terms
•Distance: Total path length covered (scalar).
•Displacement: Shortest distance between initial and final position in a given direction (vector).
•Speed: Rate of change of distance with time (scalar). Average Speed = Total Distance ÷ Total
Time.
•Velocity: Rate of change of displacement with time (vector). Average Velocity = Displacement ÷
Time.
•Acceleration: Rate of change of velocity with time (vector).
3. Types of Motion
•Uniform Motion: Equal distances covered in equal time intervals.
•Non-uniform Motion: Unequal distances in equal time intervals.
•Uniformly Accelerated Motion: Constant acceleration throughout the motion.
4. Equations of Motion (Uniform Acceleration)
•v = u + at
•s = ut + 1/2 at²
•v² = u² + 2as
•Where: u = initial velocity, v = final velocity, a = acceleration, t = time, s = displacement.
5. Graphical Representation of Motion
•Distance–Time Graph: Slope = Speed.
•Velocity–Time Graph: Slope = Acceleration, Area under graph = Displacement.
•Acceleration–Time Graph: Area under graph = Change in velocity.
6. Free Fall
•Motion under gravity alone.
•Acceleration = g (≈ 9.8 m/s² on Earth).
•Equations of motion apply with a = g.
7. Relative Velocity
•Velocity of one object as observed from another moving object.
•Example: Car A at 60 km/h and Car B at 40 km/h (same direction). Velocity of A relative to B =
20 km/h.
8. Projectile Motion
•An object thrown at an angle to the horizontal follows a parabolic path.
•Horizontal velocity = constant.
•Vertical motion = uniformly accelerated (due to gravity).
•Time of flight: T = (2u sinθ) / g.
•Range: R = (u² sin 2θ) / g.
•Maximum height: H = (u² sin²θ) / 2g.
9. Key Points to Remember
•Kinematics studies how objects move, not why they move.
•Differentiate between scalar (magnitude only) and vector (magnitude + direction).
•Equations of motion are valid only under constant acceleration.
