Pre-Q Physics 2019 Flashcards
What are the 7 base units
Second, metre, mole, kilogram, ampere, kelvin, candela
How to work out absolute error
Measured value - accepted value
How to work out percentage error
(Error in measurement / accepted value) x 100
What is accuracy of a measurement
How close measurement is to true value
What is precision of a measurement
1) How close each answer is to eachother
2) To how many sig. fig. it measures.
Weight formula
Mass x Gravity
Density Formula
Mass / Volume
What is a scalar
A measurement with only a magnitude (size)
What is a vector
A measurement with magnitude and direction
Average speed formula
Distance travelled / time taken
Velocity formula
displacement / time taken
acceleration formula
△velocity / △time
What are the 5 suvat equations.
- v = u + at
- s = ut + 1/2at^2
- v^2 = u^2 + 2as
- s = 1/2(u+v) t
- s = ut - 1/2at^2
What does suvat stand for
s = displacement u = initial velocity v = final velocity a = acceleration t = time taken
Newtons 1st law
A body’s motion will remain constant unless acted upon by an unbalanced external force.
Newtons 2nd law
F = m x a
Newtons 3rd law
Every force has an equal and opposite reaction
What is hooke’s law
F = kx
Circular motion formula - centripetal force
F = mv^2 / r
Moment formula
Moment = force x perpendicular distance from pivot
Momentum formula
Momentum = mass x velocity
What is impulse
force x time - equal to change in momentum
Force of impact formula
Force = change in momentum / time taken
When two or more bodies act on eachother their _________ remains constant.
momentum - Pbefore = Pafter
Work done formula
Work done (J) = Force x distance moved in direction of force
Power in terms of work done formula
Power (W) = work done / time taken
Kinetic energy formula
Ek = 1/2mv^2
Change in GPE formula
mass x gravity x change in height
efficiency formula
Efficiency = Useful energy output / Total energy input
Pressure in solids formula
Pressure = Force / Area
Pressure in liquids formula
Pressure = Depth of liquid (m) x Density x Gravity
temperature definition
(scalar) measure of average kinetic energy of particles
specific heat capacity definition
the amount of heat needed to raise the temperature of 1kg substance by 1K
specific latent heat definition
the amount of energy per kilogram required to change the phase of the substance at constant temperature.
What is boyle’s law
pressure of gas is inversely proportional to volume at constant temperature. P1V1=P2V2
What is charles’ law
Volume is directly proportional to temperature at constant pressure. V1/T1=V2/T2
What is guy lussac’s law
Pressure is directly proportional to temperature of gas at constant volume. P1/T1=P2/T2
What is combined gas law
P1V1/T1=P2V2/T2
What is conduction
The transfer of heat through physical contact
What is convection
The transfer of heat through fluids
What is Radiation
The transfer of internal energy in the form of electromagnetic waves.
The amount of thermal energy an object can absorb or emit via conduction depends on
- The amount of particles in an object (mass)
- The forces between the particles (material)
Specific heat capacity formula
Q=m x c x ΔΘ
Thermal expansion refers to ___________
The fractional change in the size of material in response to a change in temperature
What is a pulse
A single wave
What is amplitude
Maximum displacement from resting postion
What is Wavelength
Distance between two consecutive points in a phase
What is a period
Time of one full oscillation
What is frequency
Number of oscillations per unit of time
Speed of wave formula
v = λf
Wave behaviour in reflection
Angle of incidence = Angle of reflection
Wave behaviour when light enters more dense medium
Light refracts towards medium
Wave behaviour when light enters less dense medium
Light refracts away from medium
Snells law formula
n = sin i/sin r
refractive index in terms of speed of light formula
n = c/v
refractive index in terms of critical angle formula
n = 1/sin c
Which wave has longest wavelength
radio waves
Which wave has shortest wavelength
gamma rays
The gradient of a line in a speed/time graph represents -___________
acceleration
Higher density means ________ refractive index
higher
What are the 6 colours of visible light dispersed (in order)
red orange yellow green blue violet
Kirchoff’s first law
Charge is conserved around a closed circuit
Total current input = total current output
Kirchoff’s second law
Sum of EMF’s around circuit = sum of potential difference
What does EMF stand for
Electromotive force (V)
Whats’s ohm’s law formula
V=IR
When an LDR is in the dark, its resistance is _____, and v.v
high
When thermistor is hot, resistance is _____, and v.v
low
How to calculate % uncertainty
(absolute uncertainty / total reading) x 100
to calculate reading with zero error:
take away positive zero error,
add negative zero error
How to estimate random error
(0.5 x range) - absolute uncertainty
In a magnetic field, lines go from _______ to ________
north to south
Vrms - how to calculate
Peak amplitude / √2
What is Lenz’s law
Induced current flows to create internal magnetic field inside loop that opposes change in flux.
What is faraday’s law
Size of induced voltage = rate of change of flux cutting through loop.
Formula for flux
V = (delta flux/delta time)
Formula for magnetic field strength
B = flux / area
When alpha decay occurs, the atom loses:
2 protons and 2 neutrons
When beta decay occurs, the atom loses:
Gains one neutron
