AQA GCSE Engineering 8852: engineering equations and symbols

textbook pg215!!

Area of a rectangle

A = L × W

Area of a circle

A = πr²

Area of a triangle

A = ½ × b × h

Volume of a cuboid

V = L × W × H

Volume of a cylinder

V = πr² × L

Density

ρ = m / V

What does density mean?

Mass per unit volume

Stress

σ = F / A

What does stress mean?

Force per unit area

Strain

ε = Δl / l

What does strain mean?

Change in length divided by original length

Young's modulus

E = σ / ε

What does Young's modulus mean?

A measure of stiffness

Pressure

P = F / A

What does pressure mean?

Force per unit area

Factor of safety

FoS = yield stress / load

Ohm's law

I = V / R

Resistance in series

R_total = R₁ + R₂ + ...

Resistance in parallel

1 / R_total = 1/R₁ + 1/R₂ + ...

Gear ratio

Gear ratio = teeth on driven / teeth on driver

Velocity ratio

Velocity ratio = output size / input size

Mechanical advantage

MA = load / effort

What does mechanical advantage mean?

How much a mechanism reduces the effort needed

=

Equal to

<

Less than

≤

Less than or equal to

>

Greater than

≥

Greater than or equal to

±

Plus or minus

∝

Proportional to

≈

Approximately equal to

π

Pi (3.14)

ρ

Density

σ

Stress

ε

Strain

F

Force

A

Area

V

Volume

m

Mass

P

Pressure

E

Young's modulus

I

Current

R

Resistance