Equations Flashcards
Weight
Weight = mass x gravitational field strength
W = m x g
Work done
Work done = force x distance (along the line of action of the force)
(W = F x s)
Force applied to a spring
Force applied to a spring = sting constant x extension
F = k x e
Moment of a force
Moment of a force = force x distance (normal to direction of force)
M = F x d)
Pressure
Pressure = force normal to a surface ÷ area of that surface
p = F ÷ a
Distance travelled
Distance travelled = speed x time
s = v x t
Acceleration
Acceleration = change in velocity ÷ time taken
a = Δv ÷ t
Resultant force
Resultant force = mass x acceleration
F = m x a
Momentum
Momentum = mass x velocity
p = m x v
Kinetic energy
Kinetic energy = 0.5 x mass x (speed) ²
Ek = 0.5m x v ²
Gravitational potential energy
Gravitational potential energy = mass x gravitational field strength x height
(Ep = m x g x h)
Power
Power = energy transferred ÷ time
(P = E ÷ t)
OR power = work done ÷ time
(P = W ÷ t)
Efficiency
Efficiency = useful output energy transfer ÷ total input energy transfer
OR efficiency = useful power output ÷ total power input
Wave speed
Wave speed = frequency x wavelength
v = f x λ
Charge flow
Charge flow = current x time
Q = I x t
Potential difference (voltage)
Potential difference = current x resistance
V = I x r
Power
Power = potential difference x current
(P = V x I)
However p.d. = current x resistance so this can also be written as
Power = (current) ² x resistance
(P = I ² x R)
Energy transferred
Energy transferred = power x time
(E = P x t)
OR energy transferred = charge flow x potential difference
(E = Q x v)
Density
Density = mass ÷ volume
ρ = m ÷ v
Change in internal energy
Change in internal energy = mass x specific heat capacity x temperature change
(E = m x c x ΔT)
