Physics Extra, stuff I forget

Range

Symbol: R; Definition: Total horizontal distance in projectile motion; Equations: R = (u² sin 2θ)/g; Unit: m; SI Unit: m

random uncertainty

uncertainty produced by unknown and unpredictable variations in experimental situation

systematic error

error associated with instrument or experimental technique that causes measured value to be off

Newton’s first law

object at rest stays at rest, object in motion stays in motion, unless acted on by an external force (inertia)

Newton’s second law

F=ma, force causes an object to accelerate in direction of force

Newton’s third law

All forces have an equal and opposite reaction

Translational equillibrium

net force = 0

Impulse - J

change in momentum

Law of conservation of momentum

total momentum of isolated system remains constant

Law of conservation of energy

total energy of isolated system remains constant

elastic collision

kinetic energy conserved, objects do not stick together

inelastic collision

kinetic energy NOT conserved, objects stick together

Power - P

rate at which work is done, rate at which energy is transferred (joules per second J/s, or Watts, or Nm/s)

Newton’s universal law of gravitation

F=GMm/r², assuming point masses

Gravitational field strength - g

gravitational force per unit mass (on a point mass)

Gravitational Potential Energy - Ep

work done in moving a mass from infinity to a point in space (always minus, at infinity distance is 0)

Gravitational Potential - V

work done per unit mass in moving a mass from infinity to a point in space

Kepler’s third law

T² proportional to R³

Internal Energy - U

total potential energy and random kinetic energy of the molecules of a substance

mol

amount of substance that contains exactly 6.022×10²³ atoms, 1mol = grams x mass number of atom

Thermal capacity - C

energy required to raise the temperature of a substance by 1K

Specific heat capacity - c

energy required per unit mass to raise the temperature of a substance by 1K

Ideal Gas

No IMF, negligible volume (point mass), perfectly elastic collisions

Real Gas deviation from ideal gas

A real gas behaves like ideal gas under low pressure/density (increased volume makes the actual volume of the particles negligible) high temperature (increased kinetic energy makes IMF negligible)

First law of thermodynamics

U = change in U + W (thermal energy transferred to system from surroundings is = to work done by system + change in internal energy)

Isochoric (isovolumetric)

process occurs constant volume

isobaric

process occurs constant pressure

isothermal

process occurs constant temperature

adiabatic

process occurs without exchange of thermal energy (Q=0)

entropy - S

expresses degree of disorder in the system

second law of thermodynamics

entropy of the universe is increasing, implies thermal energy cannot spontaneously transfer from systems

SHM

simple harmonic motion, acceleration of object - proportional - displacement from equillibrium, acceleration always directed towards centre (equillibrium)

Resonance

system oscillates with maximum amplitude when driven by a force at a frequency equal to its natural frequency

Continuous progressive (travelling) wave

wave involves transfer of energy, no transfer of matter

Transverse wave

direction of energy transfer perpendicular to direction of particle motion (cannot be propagated in gases)

Longitudinal wave

direction of energy transfer parallel to direction of particle motion (sound waves)

Compression (waves)

area of high pressure in longitudinal wave

Rarefraction (waves)

area of low pressure (expansion) in longitudinal wave

Intensity - I

power recieved per unit area (for wave, intensity is proportional to amplitude²)

Snell’s law

n1/n2=sin02/sin01

Diffraction

bending of a wave around obstacle (diffraction only noticeable when slit width is smaller than or same size as wavelength)

Principle of Superposition

when two waves meet, the resultant displacement is the sum of vector displacements of component waves

Path difference

the difference in distance traveled by two coherent waves (d1-d2) from their sources to a specific point of intersection, either point of maximum or minimum.