Physics formulas explained and solved in full. Each page keeps the units attached at every step, because in physics a right number with a wrong unit is simply a wrong answer.
Formulas in this section
- Newton’s second lawF = maThe force needed to accelerate a mass, and what that force produces.Grades 9–10
- The equations of motionv = u + at, s = ut + ½at², v² = u² + 2asGive any three of u, v, a, s and t; the other two follow.Grades 9–12
- Projectile motionR = u² sin 2θ ⁄ g, H = u² sin²θ ⁄ 2g, T = 2u sin θ ⁄ gRange, greatest height and time of flight for something launched at an angle.Grades 11–12
Units and signs are where the marks go
Physics questions punish two things: mixing up which quantity is which, and losing track of units halfway through. Every solver here labels each quantity as it substitutes it and carries the unit right to the last line, so you can see where a stray factor of a thousand would have crept in.
Where a formula has a sign convention — and most of the motion formulas do — the working says which direction has been taken as positive, and what a negative answer means.