AS Physics Formulas and Definitions

Total Resistance in a Parallel Circuit

- 1/Resistor 1 + 1/Resistor 2 + 1/Resistor 3 + ...... (1/Rp = 1/R1 + 1/R2 + 1/R3 + .......)

Newtons 1st Law

- A body will continue in its state of rest or uniform motion in a straight line unless an external, unbalanced force acts upon it.

Inelastic

- A collision of which kinetic energy is lost or converted into other forms

Elastic

- A collision of which no kinetic energy is lost or converted into other forms

Mass

- A measure of inertia of a body (The reluctance of a body to change its motion)

Vector

- A physical quantity that has both a magnitude and a direction

Scalar

- A physical quantity that has magnitude but no direction

Random Error

- An error or uncertainty that can be above or below the correct value, due to fluctuations in experimental procedures or conditions

Systematic Error

- An error or uncertainty that has a constant value, is due to apparatus or experimental conditions. Can be allowed for and eliminated. Eg. Zero Error

Charge

- Current x Time (Q = It)

Displacement

- Distance moved in a particular direction

Velocity

- Distance/Time (d/t) - Units: ms^-1 - Rate of change of displacement, speed in a particular direction

Torque of a Couple

- Force x Distance between the 2 forces

Pressure

- Force/Area (P = F/A) - Density x Force of Gravity x Height (P = pgh) where 'p' is equal to density

Velocity of a Wave

- Frequency x Wavelength (v = fλ)

Moment of a Force

- Magnitude of a Force x Perpendicular distance between the pivot and the force

Force

- Mass x Acceleration (F = ma) - Force is the rate of change of momentum (p/t) - For a Hookes Law Spring (F = Kx) - The rate of change of momentum of a body

Weight Force

- Mass x Gravity (W = mg) - Force on a body due to a gravitational field

Density

- Mass/Velocity (p = m/v)

Diffraction Separation

- Order of Diffraction x Wavelength = Distance between lines x Sin(Angle between lines) (nλ = dsinx)

Electromotive Force

- Potential Difference across r (Internal Resistance) + Potential Difference across R (A Resistor) (E = Ir + IR)

Total Resistance in a Series Circuit

- Resistor 1 + Resistor 2 + Resistor 3 + ....... (Rs = R1 + R2 + R3 + .....)

Newtons 2nd Law

- The acceleration of a body is directly proportional to the amount of force applied and takes place in the direction of the force

Centre of Gravity

- The point on a body through which the weight effectively acts

Equilibrium

- The point where the sum of all forces about a point = 0 and the total moment about the forces is also = 0

Work

- The product of the force acting on an object and the distance moved by the object in that direction

Principle of Moments

- The sum of all clockwise moments are = to the sum of all anti-clocwise moments are

Principle Conservation of Momentum

- The total linear momentum of a system is conserved unless an external unbalanced force acts upon it

Upthrust

- The upwards force that is exerted on a body that is wholly or partially immersed in a liquid due to pressure differences between the top and bottom of the body

Newtons 3rd Law

- To every action force there is an equal and opposite reaction force

Acceleration

- Velocity/Time (v/t) - Units: ms^-2 - Rate of change of velocity

Power

- Voltage x Current - Current^2 x Resistance - Voltage^2/Resistance

Youngs Modulus Slits Experiment Equation

- Wavelength = Distance between slits x Average fringe separation/Distance from slits to screen (λ = ax/D)

Power

- Work Done/Time (P = W/t) - Force x Velocity (P = Fv) - Power is the rate of change of work done with respect to time

Voltage

- Work/Charge (V = W/Q) - Current x Resistance (V = IR)

Four Kinematics Equations

- v = u + at - v^2 = u^2 + 2as - s = ((u + v)/2) x t - s = ut + 1/2 at^2

Kinetic Energy

1/2 x Mass x Velocity^2 (Ek = 1/2mv^2)

Frequency of a Wave

1/Time (F = 1/t)

Torque

2Fd, where d is the distance from the point of which the object rotates to the force that is being applied.

Strain

Extension/Original Length (e = x/L)

Work Done

Force x Distance (W = Fd) The distance is in the direction of which the force is applied.

Stress

Force/Area (o = F/A) where the area is equal to the cross-sectional area of the wire

Distance

Length of a path, no direction

Elastic Potential Energy

Mass x Height x Acceleration due to gravity (Ep = mgh) OR for a Hookes Law Spring 1/2 x Spring Constant x Extension (1/2kX^2)

Momentum

Mass x Velocity (P = mv)

Speed

Rate of change of distance

Resistance

Resistivity x Length/Area (R = pL/A)

Young's Modulus for a Hookes Law Spring

Stress/Strain (E = o/e)