Engineering/Physics Equations
By DarthVader
Date: 2021-10-25
Topic: 71 see comments
Post views: 32066
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Pressure:
P = F / A
P = Pressure
F = Force
A = Area
Young's Modulus:
Young's modulus = Stress / Strain
E = σ / ε
σ = Stress (N m-2)
ε = Strain (no units)
Young's modulus is a measure of stiffness in a material and is found from the gradient of a stress, strain graph
Stress:
Stress = Force / Area
σ = F / A
σ = Stress (N m-2)
F = Force (N)
A = Area (m2)
Momentum:
Momentum = Mass × Velocity
P = mv
P = Momentum (kg m s-1)
m = Mass (kg)
v = Velocity (m s-1)
Impulse:
(Impulse = Change in momentum)
Change in Momentum = Force × Time
ΔP = FΔt
Force = Change in Momentum / Time
F = ΔP / ΔT
(can also be written: F = mv2 - mv1 / t )(alternative version of Newtons second law (F = ma))
Ft = Δ(mv)
SI Unit = N s (kg m s-1)
Specific Heat Capacity:
ΔQ = mcΔT
m = ΔQ / cΔT
ΔT =ΔQ / mc
ΔQ = Heat Energy (J)
m = Mass (kg)
c = Specific Heat Energy (J / kg °C) - [ Joules per kilogram per degree celsius]
ΔT = Temperature Difference (k) (°C)
Specific latent heat of fusion:
ΔQ = mLf
ΔQ = Heat Energy (J)
m = Mass (kg)
Lf = Latent heat of fusion (J kg-1)
Potential Energy:
Ep = mgh
m = EP / gh
h = EP / mg
Ep = Potential Energy (J)
m = mass (kg)
g = Gravity (N) (9.81)
h = Height (m)
Ep = Wh
W = Weight (N)
h = Height (m)
This is because the potential energy is equal to the force required to lift it times the height it is lifted to.
Kinetic Energy:
Ek = ½mv2
m = 2Ek / v2
v = √ 2Ek / m
Ek = Kinetic Energy (J)
m = Mass (kg)
v2 = Velocity Squared (m s-1)
Note: Don't forget to multiply by 2 to get rid of the fraction when re-arranging the equation.
Work Done (energy transferred):
Work done = force × distance
W = Fd
W = Work done in J (joules)
F = Force in N (newtons)
d = distance in m (meters)
Power:
P = W / t
P = Power in W (watts)
W = Work done in J (joules)
t = Time in s (seconds)
Efficiency:
Efficiency = Useful Output / Input
%Efficiency = Useful Output /Input × 100%
Max possible efficiency is 1 or 100% as energy cannot be created, ‘you get out what you put in’
Input = Useful Output / %Efficiency
Weight:
Weight = Mass × Gravitational constant
(W = mg)
Measured in N (newtons)
Mass:
Mass = Volume × Density
m = vp
p = Density
HINT:
Mass can be used to get Weight and Weight can be used to get Force
Force:
Force = Mass × Acceleration
(F = ma)
Newtons 2nd law of motion
Measured in N (newtons)
========================>
Force = Change in Momentum / Time
F = ΔP / ΔT
Acceleration:
Acceleration = Change in Velocity / Time
Measured in ms-2
Speed:
Speed = Distance / Time
Measured in ms-1
Velocity:
Velocity = Displacement / Time
Strain:
Strain = Expansion / Original length
(ε = Δl / l1)
Density:
Density = Mass / Volume
The symbol used to represent density is the greek letter p (rho)
The unit is ‘mass per unit volume’, written: kg m-3. ( kilograms per cubic metre )
Equation for Density:
P = m / v
m = Mass
v = Volume
p = m / v
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