F = ma and circular motion

Cambridge IGCSE Physics 0625 · 2026–2028 v2 · Original learning materials.

Scalars have size only and vectors have size and direction (1.1.4); distance, speed, time, mass, energy and temperature are scalars (1.1.5); force, weight, velocity, acceleration, momentum, electric field strength and gravitational field strength are vectors (1.1.6); the resultant of two vectors at right angles, by scale drawing and by calculation, for forces and velocities only (1.1.7); the resultant of two or more forces along the same straight line (1.5.1.3); with no resultant force an object stays at rest or moves in a straight line at constant speed (1.5.1.4); a resultant force changes the velocity of an object by changing its speed or its direction of motion (1.5.1.5); F = ma, with the force and the acceleration in the same direction (1.5.1.11); motion in a circular path due to a force at right angles to the motion: with the mass and the radius constant, a bigger force goes with a bigger speed; with the mass and the speed constant, a bigger force goes with a smaller radius; with the speed and the radius constant, a bigger mass needs a bigger force (1.5.1.12). 1.1.4–7, 1.5.1.11 and 1.5.1.12 are Supplement. F = mv²/r is not required and is not used. Springs are in Stretching springs, friction and drag in Acceleration, falling and drag, moments in Moments and balance, and momentum in Momentum and collisions.

Apparatus, amounts and times in the experiment are illustrative. Real practical work follows a teacher-approved safety method.