Key equations Flashcards
Average speed =
Distance / time
Distance =
Average speed x time
Acceleration =
And another version which starts with v^2 - u^2 = …
Change in velocity / time taken
a= (v-u)/t
V^2 - u^2 = 2 x a x X
X stands for distance
What is Newton’s second law? The equation for force?
F=m x a
Weight=
Mass x gravitational field strength
W = m x g
What is Earths gravitational field strength?
10 N/kg
9.81 rounded
Momentum =
Mass (kg) x velocity
P = m x v
Change in gravitational potential energy (Joules)=
Mass x gravitational field strength x change in vertical height
^GPE = m x g x ^h
Kinetic energy (Joules) =
1/2 x m x v^2
Efficiency =
Useful energy transferred / total energy supplied
Wave velocity =
State both equations
Wave velocity = frequency x wavelength
Wave velocity = distance / time
What is the equation for force which includes momentum ?
Force = change in momentum / time F = (mv - mu) / t
What is the equation for work done?
Work done = force x distance
What is the equation for power? A measure of how quickly work done is being done
Power = work done / time
What is the equation for work done (measured in joules) ?
E = F x d
Work done in Joules= force in N x distance moved in direction of force
What is the equation for power in watts?
P = E/t Power = Energy transferred in joules / time
What is the equation for energy transferred in joules?
E = Q x V
Energy transferred in joules = Charge in coulombs x potential difference in volts
What is the equation for potential difference in volts?
V = I x R
Potential difference in volts = current in amps resistance in Ohms
What is the equation for charge in coulombs (C)?
Q = I x t
Charge in coulombs = current in amps x time
What is the equation (one out of 2) for power in watts, including potential difference in volts?
P = I x V
Power in watts = current in amps x potential difference in volts
What is the equation (one out of 2) for power in watts,including resistance in ohms (measured with Greek letter Omega)?
P = I(squared) x R
Power in watts = current in amps (squared) x resistance in ohms
What is the equation for density in kg/m(cubed) or g/cm(cubed)?
p (lower case Greek letter rho) = m / V
Density in kg/m(cubed) or g/cm(cubed) = mass in kg/ volume in m or cm (cubed)
What is the equation for pressure in N/m(squared) or N/cm(squared)?
P = F/ A
Pressure in N/m or N/cm (squared) = Force in N / Area in m or cm (squared)
What is the equation for Force in N, including spring constant and extension?
F = k x X
Force in N = spring constant (in N/m, N/cm or N/mm) x extension (in m, cm or mm)
