IGCSE 0625 · MECHANICS · 1.5

Forces

Resultant forces and Newton's second law, Hooke's law, and moments and stability. It builds on motion and mass, and leads into momentum and energy.

TOPIC 1.5: FORCES CAMBRIDGE IGCSE PHYSICS 0625 · PATHWAYS TheLucidSTEM · thelucidstem.com BUILDS ON 1.2 Motion 1.3 Mass LEADS TO 1.6 Momentum 1.7 Work & energy FORCES & NEWTON 1 · FORCES & RESULTANT 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 that has the same effect as all of them together. Balanced: rest or steady speed. Unbalanced: it accelerates. friction push unbalanced → it accelerates 2 · NEWTON'S SECOND LAW A resultant force makes a mass accelerate. F = m a F = resultant force (N) The bigger the force, the bigger the acceleration. The bigger the mass, the smaller the acceleration. Friction and drag oppose motion; drag grows as an object moves faster. 3 · HOOKE'S LAW Up to a limit, a spring's extension is proportional to the load. F = k x k = spring constant x = extension load extension limit of proportionality 4 · MOMENTS & STABILITY A moment is the turning effect of a force. moment = F × d d is the perpendicular distance from the pivot. For balance: total clockwise = total anticlockwise. small force, far away big force, near pivot balanced when force × distance is equal on both sides A low centre of gravity and a wide base give stability.
TOPIC 1.5: FORCES CAMBRIDGE IGCSE PHYSICS 0625 · PATHWAYS TheLucidSTEM · thelucidstem.com BUILDS ON 1.2 Motion 1.3 Mass LEADS TO 1.6 Momentum 1.7 Work & energy FORCES & NEWTON 1 · FORCES & RESULTANT 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 that has the same effect as all of them together. Balanced: rest or steady speed. Unbalanced: it accelerates. friction push unbalanced → it accelerates 2 · NEWTON'S SECOND LAW A resultant force makes a mass accelerate. F = m a F = resultant force (N) The bigger the force, the bigger the acceleration. The bigger the mass, the smaller the acceleration. Friction and drag oppose motion; drag grows as an object moves faster. 3 · HOOKE'S LAW Up to a limit, a spring's extension is proportional to the load. F = k x k = spring constant x = extension load extension limit of proportionality 4 · MOMENTS & STABILITY A moment is the turning effect of a force. moment = F × d d is the perpendicular distance from the pivot. For balance: total clockwise = total anticlockwise. small force, far away big force, near pivot balanced when force × distance is equal on both sides A low centre of gravity and a wide base give stability.
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