Motion — kinematics for CCEA Double Award Physics
Key quantities
Distance: how far an object has travelled in total (scalar — direction not specified). Displacement: the straight-line distance and direction from start to end (vector).
Speed: distance ÷ time (scalar). v = d/t. Velocity: displacement ÷ time (vector — includes direction). v = s/t.
Acceleration: the rate of change of velocity. a = (v − u)/t. Where v = final velocity, u = initial velocity, t = time.
Units: distance — m; time — s; speed/velocity — m/s; acceleration — m/s².
Key equations (CCEA provides these in the exam)
| Equation | Use |
|---|---|
| v = d/t or s = vt | Uniform speed/velocity |
| a = (v − u)/t | Finding acceleration |
| v² = u² + 2as | Finding final velocity without time |
| s = ut + ½at² | Finding displacement with time |
Note: CCEA Double Award Physics usually only requires the first two for Foundation tier; Higher tier uses all four.
Distance-time graphs
| Gradient | Meaning |
|---|---|
| Zero (horizontal) | Object is stationary |
| Positive constant | Constant speed |
| Positive increasing | Accelerating |
| Negative | Moving back towards start |
Gradient of a distance-time graph = speed.
Velocity-time graphs
| Feature | Meaning |
|---|---|
| Gradient | Acceleration |
| Positive gradient | Speeding up |
| Zero gradient (horizontal) | Constant velocity |
| Negative gradient | Decelerating |
| Area under curve | Distance (displacement) |
Two key rules: gradient of v-t graph = acceleration; area under v-t graph = distance.
Calculating from graphs
Speed from d-t graph: choose two points on the straight line; speed = (change in distance) ÷ (change in time) = Δd/Δt.
Acceleration from v-t graph: gradient = (change in velocity) ÷ (change in time) = Δv/Δt.
Distance from v-t graph: area under the line (rectangle + triangle for non-uniform sections).
Typical CCEA context
CCEA Physics P1 papers include graph reading questions set in contexts like a car journey through Belfast, a cyclist, or a ball dropped from a building. Reading, drawing, and calculating from graphs is heavily tested.
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