Hertz to Degrees per hour
Hz
°/h
Conversion History
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Quick Reference Table (Hertz to Degrees per hour)
| Hertz (Hz) | Degrees per hour (°/h) |
|---|---|
| 20 | 25,920,000 |
| 50 | 64,800,000 |
| 60 | 77,760,000 |
| 440 | 570,240,000 |
| 1,000 | 1,296,000,000 |
| 20,000 | 25,920,000,000 |
About Hertz (Hz)
The hertz (Hz) is the SI unit of frequency, defined as one cycle per second. It is the base unit from which all other frequency units are derived by decimal prefix. Hertz is used across an enormous range of applications: electrical mains frequency (50 or 60 Hz), the lower edge of human hearing (~20 Hz), and up through audio, radio, and computing frequencies. A sound of 440 Hz is the musical note A4, the standard orchestral tuning pitch. The hertz replaced the older term "cycles per second" when it was adopted by the SI in 1960.
Mains electricity in Europe alternates at 50 Hz; in North America at 60 Hz. The concert A pitch is 440 Hz. Human hearing spans roughly 20 Hz to 20,000 Hz.
Etymology: Named after German physicist Heinrich Rudolf Hertz (1857–1894), who first conclusively demonstrated the existence of electromagnetic waves predicted by Maxwell's equations. The unit was adopted by the General Conference on Weights and Measures in 1960.
About Degrees per hour (°/h)
Degrees per hour (°/h) is used for very slow angular motions, particularly in navigation, geophysics, and astronomy. High-precision gyroscopes are rated by their drift in °/h — a navigation-grade ring-laser gyro may drift less than 0.01°/h, while a consumer MEMS gyro drifts hundreds of degrees per hour. Earth's rotation corresponds to 15°/h (360° ÷ 24 h), which is why the Sun appears to move 15° per hour across the sky. Telescope drive motors use this rate to compensate for Earth's rotation during long exposures.
Earth rotates at exactly 15°/h, so astronomical telescope drives track stars at 15°/h. Navigation-grade laser gyroscopes achieve drift below 0.01°/h. The Moon moves about 0.55°/h against the background stars.
Hertz – Frequently Asked Questions
Why does Europe use 50 Hz mains electricity while North America uses 60 Hz?
It is largely a historical accident. Early generators in the US settled on 60 Hz because it divided neatly by common motor pole counts and worked well with the 110 V supply Edison promoted. Germany standardized on 50 Hz with a 220 V supply, and colonial-era wiring spread each standard across continents. Changing now would mean replacing every motor, transformer, and clock in the country — so both standards persist.
What is the deal with 432 Hz vs 440 Hz tuning — does it really matter?
Concert pitch A4 = 440 Hz was standardized internationally in 1955, but some musicians insist 432 Hz sounds warmer or more natural. There is no physics-based reason 432 is special — it is 8 Hz lower, which shifts every note slightly flat. Historical tuning varied wildly (baroque pitch was often ~415 Hz). The debate is real in music circles, but the claimed health benefits of 432 Hz have no scientific support.
How did Heinrich Hertz prove electromagnetic waves exist?
In 1887 Hertz built a spark-gap transmitter and a loop antenna receiver in his lab in Karlsruhe. When the transmitter sparked, the receiver — across the room with no wire connecting them — also sparked. He measured the wavelength and speed, confirming they matched Maxwell's theoretical predictions for light. Hertz was 30 years old. Ironically, he called the discovery of no practical use.
Why do fluorescent lights sometimes flicker at 50 or 60 Hz?
Older magnetic-ballast fluorescent tubes ignite and extinguish twice per mains cycle (100 or 120 times per second) because AC current crosses zero twice per cycle. Most people can't consciously see 100 Hz flicker, but it can cause headaches and eye strain. Modern electronic ballasts drive the tube at 20–40 kHz, eliminating visible flicker entirely.
What is the lowest frequency a human can hear?
About 20 Hz under ideal conditions, though sensitivity at that frequency is poor — you need extremely high sound pressure to perceive it. Below 20 Hz is infrasound: you cannot hear it as a tone, but at sufficient intensity you feel it as chest pressure or unease. Pipe organs exploit this: their longest 64-foot pipes produce notes around 8 Hz that you feel more than hear.
Degrees per hour – Frequently Asked Questions
How fast does the International Space Station orbit in degrees per hour?
The ISS completes one orbit (360°) in about 92 minutes, giving roughly 235°/hr — almost 16 times faster than Earth's rotation. That is why astronauts see 16 sunrises every 24 hours. At an altitude of ~408 km, the station covers about 7.66 km/s of ground track. If you could watch it from a fixed point in space, it would visibly sweep through the sky at a rate where one degree takes only about 15 seconds.
Why are gyroscope drift rates measured in degrees per hour?
Because even tiny drift accumulates into serious navigation errors over a flight or voyage. A navigation-grade ring-laser gyroscope drifts less than 0.01°/hr; over a 10-hour flight that is only 0.1° of heading error. A cheap MEMS gyro drifting 10°/hr would accumulate 100° of error in the same time — useless for navigation. Expressing drift in °/hr makes the operational impact immediately obvious to a pilot or engineer.
How do telescope mounts use the 15°/hr rate for star tracking?
Equatorial telescope mounts have a motorised right-ascension axis aligned with Earth's rotation axis. By driving that axis at exactly 15°/hr (one sidereal rate), the telescope counter-rotates against Earth's spin, keeping a star fixed in the eyepiece. Without this drive, stars would drift out of view in seconds at high magnification. Astrophotographers rely on it for long exposures without star trails.
How fast does the Moon move across the sky in degrees per hour?
The Moon's apparent motion has two components. It shares the sky's overall 15°/hr westward motion due to Earth's rotation. But it also orbits Earth, moving about 0.55°/hr eastward relative to the stars (360° ÷ 27.32 days ÷ 24 hr). The net effect: the Moon moves westward across the sky at roughly 14.5°/hr, which is why moonrise occurs about 50 minutes later each day.
Why does a Foucault pendulum appear to rotate at fewer than 15°/hr at most latitudes?
A Foucault pendulum's swing plane rotates relative to the floor at 15° × sin(latitude) per hour. At the North Pole (90°) that is the full 15°/hr; at 45° latitude it is about 10.6°/hr; at the equator it is zero. The pendulum always swings in a fixed plane in inertial space — it is the Earth rotating underneath it. The sine factor comes from the fact that only the vertical component of Earth's angular velocity vector projects into the pendulum's swing plane. Paris (48.9°N) sees about 11.3°/hr, which is why Foucault's original 1851 demonstration took most of a day to complete a visible rotation.