Forces · revision map · IGCSE 0625, Topic 1.5
TOPIC 1.5 · FORCES
CAMBRIDGE IGCSE PHYSICS 0625 · ONE-PAGE REVISION MAP
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FORCES1.5
Forces & Resultant Force
A force is a push or pull. It can change an object's shape, speed or direction. Types: weight, friction, contact, tension, drag.
The resultant is the single force with the same effect as all of them together.
Balanced forces: at rest or steady speed. Unbalanced: it accelerates.
Newton's Second Law
A resultant force makes a mass accelerate.
F = m a
F = resultant force (N)
m = mass (kg)
a = acceleration (m/s²)
m = mass (kg)
a = acceleration (m/s²)
- Bigger force → bigger acceleration.
- Bigger mass → smaller acceleration.
Friction & Drag
Friction and drag are forces that oppose motion.
- Drag grows as an object moves faster through a fluid.
Hooke's Law
Up to a limit, a spring's extension is proportional to the load.
F = k xk = spring constant
x = extension
x = extension
Moments & Balance
A moment is the turning effect of a force about a pivot.
moment = F × d
d = perpendicular distance from the pivot · unit N m
Principle of moments: in balance, total clockwise moment = total anticlockwise moment.
Centre of Gravity & Stability
The centre of gravity is the single point where an object's whole weight seems to act.
- It tips over when its line of weight falls outside the base.
- A low centre of gravity and a wide base give greater stability.