Kinematics: The Mathematics of Motion Readings: Chapter 2
Motion along a straight line Can be illustrated by position-versus-time graph: 1 s 2 s 3 s 4 s x Continuous (smooth) curve Origin (x=0) x 10 cm 20 cm 40 cm 70 cm 1 2 3 4 t(s)
Position graph x 1 sec 2 sec 3 sec 4 sec Velocity is the same – zero acceleration 1 2 3 4 t(s) Straight line – uniform motion – the same velocity Velocity is the slope
Position graph: uniform motion x Motions in opposite directions t(s)
Uniform motion: motion with constant velocity x t v t
Uniform motion: application Example: x Find and t
Position graph
realistic non-realistic
Instantaneous velocity Very small Instantaneous velocity: If dependence is given, then - derivative Example: Instantaneous velocity - slope
Finding position from velocity
v t The displacement is the area, displacement is positive v t Displacement is negative
Example: Find the net displacement C D A B area
x A C Velocity is the slope B t
Velocity is the slope Acceleration is the slope
Motion with constant acceleration Motion with constant velocity: Motion with constant acceleration:
Motion with constant velocity or constant acceleration Motion with constant acceleration: Useful relation: then
Motion with constant velocity or constant acceleration Motion with constant acceleration:
Free fall motion - motion with constant acceleration
Free fall motion - motion with constant acceleration At final point: