Motion
Speed & Velocity
Speed (scalar): v = d/t. Velocity (vector): v = Δs/Δt.
Distance–Time Graphs
- Slope = speed; straight line = constant speed; horizontal = rest.
- Curved line ⇒ changing speed; tangent’s slope = instantaneous speed.
Speed/Velocity–Time Graphs
- Slope = acceleration; area under graph = distance (or displacement).
- Horizontal = constant velocity; straight incline = uniform acceleration.
Constant Acceleration (SUVAT)
v = u + ats = ut + ½at²v² = u² + 2as
Example
Car from rest to 20 m/s in 10 s: a = (20−0)/10 = 2 m/s²; distance = area = ½×10×20 = 100 m.
Free Fall & Terminal Velocity
- In free fall (no air resistance),
a = g ≈ 9.8 m/s²downward. - With air resistance, acceleration falls; at terminal velocity forces balance.