Newton's First & Second Laws
State and apply Newton's First Law (an object stays at rest or constant velocity unless acted on by a resultant force) and Second Law (force = mass × acceleration), including the relationship between mass, force, and acceleration
Typical age: 12–13 years
“If your child was asked why you need a seatbelt in a car but not when sitting still, could they explain what Newton's First Law says about moving objects — and then calculate how much force a 60 kg person experiences in a sudden stop?”
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Needs first
- Resultant ForcesREQUIRED
Newton's 1st and 2nd laws are defined in terms of resultant force — the concept of balanced and unbalanced forces must be understood first
- Mass vs Weight
Gravity (weight = mg) is the main worked example for Newton's laws — mass/weight distinction gives concrete numbers for F = ma
- Air Resistance & Friction
Newton's laws explain why friction and air resistance slow objects down — the KS2 observation of resistance now has a theoretical explanation
Unlocks next
- Newton's Third LawREQUIRED
Newton's Third Law is conventionally taught after the first two — students need Newton's 1st and 2nd as reference points to distinguish reaction pairs from balanced forces
- Investigating Forces
Testing F = ma experimentally requires knowing the relationship between force, mass and acceleration