Key Physics Laws and Definitions
Ever wonder why your weight changes on different planets but your mass stays the same? Weight is the force gravity puts on you (measured in Newtons), whilst mass is simply how much matter you contain (measured in kg). On Earth, gravity pulls at 9.8 N/kg (we often round this to 10 for easier calculations).
Newton's second law gives us the essential equation: Force = mass × acceleration. This means heavier objects need more force to accelerate them. When objects reach terminal velocity (like a skydiver), they stop accelerating because air resistance equals their weight - the forces balance out perfectly.
Hooke's Law explains how springs work: the extension is directly proportional to the force applied (until it breaks). Simply put, double the force and you'll double the stretch. The equation is: Force = spring constant × extension.
Key insight: The law of conservation of momentum states that in a closed system, total momentum before an event equals total momentum after - this explains everything from snooker balls to car crashes!
