Question 1

Why does the US use Fahrenheit?

Accepted Answer

Daniel Fahrenheit proposed the scale in 1724, and the US is one of the few countries that never switched to Celsius. On his scale 0°F was a freezing mix of ice, water, and salt; he set body temperature near 96°F (today taken as 98.6°F, or 37°C).

Question 2

What is absolute zero?

Accepted Answer

0 K = −273.15°C, the theoretical lowest temperature, where molecular thermal motion stops entirely. It is unreachable in practice, though labs cool matter to within billionths of a kelvin in quantum physics and laser cooling.

Question 3

How do I remember the conversion?

Accepted Answer

Anchor on two points: 0°C = 32°F and 100°C = 212°F. A 100°C span equals a 180°F span, giving the 9/5 factor. Forward: multiply by 9, divide by 5, add 32. Back: subtract 32, multiply by 5, divide by 9.

Question 4

What temperature is comfortable to live in?

Accepted Answer

Comfort sits around 20–25°C (68–77°F), with 16–19°C ideal for sleeping. Office guidelines suggest 20–25°C in winter and 21–25°C in summer. Above 40°C is dangerous, and below −30°C is dangerous without protection.

Question 5

Why bother with Kelvin?

Accepted Answer

An absolute scale with no negative values is convenient in physics, chemistry, and astrophysics. The gas law PV = nRT needs T in kelvins. Kelvin also describes the colour temperature of light: an incandescent bulb is 2,700 K, neutral white 4,000 K, and daylight 6,500 K.

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