# AS PHYSICS UNIT 1 - THINGS TO LEARN

My own revision notes on things to learn for edexcel as physics unit 1... enjoy, and good luck!

## Equations of Motion

v = final velocity

u = initial velocity

a = acceleration

t = time

s = displacement

1) v = u + at

2) v^2 = u^2 + 2as

3) s = ut + 0.5at^2

4) s = (u + v)/2 x t

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## Newtons Laws of Motion

1) An object will continue at a state of rest (or constant velocity) unless a resultant force acts upon the object.

2) Force is directly proportional to the acceleration providing mass is a constant,

i.e. F = ma

3) Each action has an opposite but equal reaction.

REMEMBER:

For Law 3...

SIMILARITIES - same type of force, same magnitude

DIFFERENCES - acting on different objects, in opposite directions

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## Resolving Vectors and Pythagoras

For those not so maths minded, a really simple way to do these questions is to learn the rule:

Vertical componants - use SIN

Horizontal componants - use COS

When finding the ANGLE, dont forget to use the INVERSE... One way to remember this is that both Angle and Inverse start with a vowel ;)

The same rules are applied with projectile motion. There is a great diagram on page 37 of the text book which shows this well (under the dartboard).

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## Conservation of Energy, Efficiency and Horsepower

The law of conservation of energy is simple:

ENERGY CANNOT BE CREATED OR DESTROYED

However, energy is transferred and for that reason we can work out its efficiency by this equation:

EFFICIENCY = (useful energy output/ total energy input) x 100%

Horsepower is a method of measuring the rate of doing work which was used before the industrial revolution.

1 Horsepower = 750 Watts

(don't forget that number!)

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## Equations You Should Really Know...

Power = energy transferred / time

Gravitational Potential Energy = mass x gravity x height

Kinetic Energy = 0.5 x mass x velocity^2

Work Done = Force x Displacement (in the direction of the force!)

Density = Mass / Volume

Force = Constant (k) x change in extension

Stokes Law (viscous drag) = 6(pi) x viscosity of the liquid (Pascal seconds - Pa s) x radius (metres) x drift velocity (ms^-1)

These may be in the formula booklet but they dont give the meanings of each term, so get familiar! :)

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## Materials

Definitions to learn:

Laminar Flow - streamline flow with no mixing, air flows in layers.

Turbulent Flow - flow with mixing of layers, forms eddies

Upthrust - weight of fluid displaced

Limit of Proportionality - when stress is proportional to strain and obeys Hooke's Law

Tensile strength - greatest stress before fracturing

Yield Point - point at which plastic deformation begins

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