Read Repeating Motion: Identify One Full Cycle
Circular motion stays at a fixed radius from a centre. Oscillation repeats about a mean position; its period is the time for one complete to-and-fro cycle.
Motion and force questions become simpler when direction, starting condition, time and the acting forces are marked first.
Use the path and the clock together
Mark start, direction and time before reading the graph
Mark a start, direction and time interval first. On a graph, the slope tells how the quantity changes; on a path, distance and displacement may differ.
Separate distance from displacement
Distance is path length; displacement is the straight-line change from start to finish. After half a lap on a circular track, displacement is the diameter, not half the circumference.
Count fractions of an oscillation
For a pendulum moving from one extreme to the mean position, the time is one-quarter of a period. Extreme to the opposite extreme is half a period.
OlympIQ exam lens
- ✓Draw the start and end positions.
- ✓Use diameter for half-circle displacement.
- ✓Mark whether the pendulum move is 1/4, 1/2 or a full period.
The mark on a rolling wheel does not travel in a circle about a fixed point; it traces a cycloid.
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