Weight Mass Force

Year 11 Review

Newtons Laws

N1 - F = 0 then a = 0, v = constant

N2 - Sum F = m x a , a = dv/dt acceleration in the direction of travel, a = v^2/r tangental acceleration
(defines both mass and force)
Units m kg, a ms-2,
applies to a body,
Multipy F= ma by d, d = (v+u)/2 x t

N3 - F12 = -F21,
applies to body contact B1 with B2, a system
Multipy F = ma by t, Ft = I = m(v -u)/t x t , Impulse = change in momentum



Year 12 Concepts

Weight
Symbol: W (vector)
Definition: Force caused by gravity - caused by the proximity to a mass.
Unit: newton N
Weight on Mars, refers to the Normal force measured by scales on the surface of Mars

Mass
Symbol: m, M for a Planet
Definition: Indirect from F = ma, W = mg, (E=mc^2 & Quantum Mechanics)
Unit: kg

gPlanet
Symbol: g for earth on surface (g = 9.8 ms-2), all others require subscript (vector)
Definition: acceleration of a mass on surface of a planet
Unit: ms-2

reaction Force
Symbol: N (vector) - Normal force on a flat surface
Defintion: reading of scales, often called mistakenly weight, N = 0 of freefall is call "weightlessness"
Unit: newtons (N)

g-measured
Defintion: What is recorded by a g measuring apparatus, and will vary from g due to altitude, Moon, Sun, spin of earth, gravitional anomolies
Unit:ms-2

g-force
Definition: N/Wearths surface
Unit: none - a ratio
Humans can only experiance a maximum g-force, g-force = 0 is free fall or weightlessness


kwnewtonslaw kwg-force kwgravity