Kinematics · revision map · A-Level 9702, Topic 2

TOPIC 2 · KINEMATICS
CAMBRIDGE INTERNATIONAL AS & A LEVEL PHYSICS 9702 · ONE-PAGE REVISION MAP
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KINEMATICS2
Describing Motion & Graphs

Position, its rate of change, and that rate's rate of change.

  • Displacement s is a vector; distance is its scalar length.
  • Velocity v = Δs / Δt; acceleration a = Δv / Δt.
  • Gradient of an s–t graph gives v; gradient of a v–t graph gives a.
  • Area under a v–t graph gives displacement s.
v = ds / dt · a = dv / dt v t area = displacement s gradient = a rise
Equations of Motion (SUVAT)

For constant acceleration: four equations, five symbols (s, u, v, a, t).

v = u + at s = ½(u + v)t
s = ut + ½at² v² = u² + 2as
  • Valid only when a is uniform.
  • List what you know; pick the equation that omits the unknown you do not need.
  • They follow from the v–t graph: gradient gives a, area gives s.
u v t s = area (trapezium)
Free Fall Under Gravity

The special case: a = g, directed downward.

  • With no air resistance, every body falls with the same g.
  • Near Earth g ≈ 9.81 m s−², taken as the only force.
  • Released from rest: s = ½gt², v = gt.
  • Time a steel ball dropped a height s to measure g.
g = 2s / t²
g
Projectile Motion

Two independent motions, one parabola.

  • Horizontal: constant velocity, no force (ignore drag).
  • Vertical: free fall, acceleration g.
  • The two share only the same clock t; solve separately.
  • Resolve the launch speed u: horizontal u·cosθ, vertical u·sinθ.
x = (u cosθ)t · y = (u sinθ)t − ½gt²
y x vx vy
BUILDS ON · Quantities & Units → KINEMATICS → LEADS TO · Dynamics · Energy · Circular Motion
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