Letter | Variable or constant | Unit | Equations with variable |
---|---|---|---|
A | amperes (current) | ||
a | acceleration | ||
BMI | body mass index | ||
c | speed of light | centi- prefix: cm | E = mc² |
d | distance | d = ѵt, d = 0.5at², d = 0.5gt² | |
Δ% | percent difference | ||
F | force | , F = ma, F = −kx | |
f | frequency f | f = 1 ÷ τ | |
h | height, Planck constant | ||
i | current, | ||
g | acceleration of gravity | grams | d = 0.5gt² |
GPE | gravitational potential energy | GPE = mgh | |
KE | kinetic energy | KE = 0.5mѵ² | |
k | Hooke's constant, y-coor. quadratic vertex | F = kx, | |
l | length | liters (liquid volume) | |
λ | wavelength | ѵ = λf | |
m | mass | meters | m = ρV |
Ω | Ohms (Resistance) | V = iR | |
P | Power | P = iV | |
p | momenturm | p = mѵ | |
ρ | density | m = ρV | |
R | Resistance | V = iR | |
s | arc length | seconds | |
T | temperature | ||
t | time | ||
τ | period | τ = 1 ÷ f | |
V | volume, voltage | Volts | V = lwh, V = iR |
ѵ | velocity | , ѵ = at | |
W | work (energy) | Watts (power) | |
w | width | V = lwh |
Web bulb depression in °C: Dry bulb minus the wet bulb | |||||||
---|---|---|---|---|---|---|---|
Dry bulb T in °C | 0.5 | 1.0 | 2.0 | 2.5 | 3.0 | 3.5 | 4.0 |
21 | 95% | 90% | 83% | 79% | 77% | 72% | 67% |
24 | 96% | 91% | 84% | 80% | 78% | 74% | 69% |
27 | 96% | 91% | 85% | 81% | 78% | 75% | 71% |
28 | 96% | 93% | 85% | 82% | 78% | 75% | 72% |
29 | 96% | 93% | 88% | 84% | 80% | 76% | 73% |
30 | 96% | 93% | 86% | 82% | 79% | 76% | 73% |
32 | 96% | 93% | 89% | 85% | 81% | 78% | 74% |
35 | 96% | 93% | 89% | 85% | 82% | 79% | 75% |
38 | 96% | 93% | 89% | 86% | 83% | 80% | 76% |
Heat index as an effective temperature in °C given a dry bulb temp. and Rel. Hum.
Dry bulb temperature in °C | ||||||||
---|---|---|---|---|---|---|---|---|
Relative humidity | 21 | 24 | 27 | 28 | 29 | 31 | 32 | 35 |
60% | 21 | 24 | 28 | 29.5 | 32 | 35 | 38 | 46 |
70% | 21 | 25 | 29 | 30.7 | 34 | 37 | 41 | 51 |
80% | 22 | 26 | 30 | 32.1 | 36 | 40 | 45 | 58 |
90% | 22 | 26 | 31 | 33.7 | 39 | 43 | 50 | |
100% | 22 | 27 | 33 | 35.6 | 42 |
Effective temperature and risk level
Effective temperature in °C: | Risk level |
---|---|
Less than 32 °C | Low risk |
32 °C to 41 °C | Heat cramps or heat exhaustion likely |
Above 41 °C | Heat stroke likely. |