Meter per Hour to Foot per Second

Most valley glaciers advance at 20–200 m/h (0.5–5 m/day). Surge glaciers — which periodically accelerate — can reach 1,000–10,000 m/h for months at a time. The Jakobshavn Glacier in Greenland holds the record for the fastest sustained glacier flow at roughly 4,600 m/h (46 m/day). For context, that's still far slower than a garden snail.

Human scalp hair grows at roughly 15 cm per year — about 0.017 mm/hour, or 0.000017 m/h. Nails grow at about half that rate. At this scale, even the m/h unit is too large; growth biologists use mm/day or cm/month. The fastest-growing human tissue is bone marrow, not hair.

Some lava flows on gently sloping terrain advance at about 1 m/h. Tectonic plates move at 2.5–15 cm/year — far below even 1 m/h. Bread rising in a warm kitchen expands at a few mm/hour. Corrosion front advancement in protected steel structures can be tracked in mm or cm per year.

m/h and m/hr are both used for meters per hour — neither is an official SI notation, since the SI symbol for hour is h (not hr). The correct SI notation is m/h. In engineering documentation, m/hr appears frequently as a stylistic choice, particularly in American engineering texts that prefer "hr" over "h" for legibility.

Multiply by 24,000. One m/h = 1,000 mm/h × 24 h/day = 24,000 mm/day. This conversion is useful in hydrology (soil permeability is measured in mm/day) and biology (plant growth, wound healing rates). A glacier moving at 100 m/h would be advancing 2,400,000 mm/day — or 2.4 km/day, which is an exceptionally fast surge.

A professional golfer's driver launches the ball at roughly 250 ft/s (170 mph). An amateur averages about 190–220 ft/s. The PGA Tour record ball speed is around 330 ft/s (225 mph), set by long-drive competitors using specialised equipment. For comparison, a tennis serve reaches about 180 ft/s and a baseball pitch about 150 ft/s — making a driven golf ball one of the fastest objects in non-motorised sport.

A skydiver in a stable spread-eagle position reaches terminal velocity at approximately 120 mph (176 ft/s) after about 10 seconds of freefall. In a head-down dive position, terminal velocity can reach 200+ mph (293+ ft/s). With a deployed parachute, descent slows to about 10–17 ft/s (7–12 mph) for a safe landing.

Vertical speed indicators in aircraft (VSI) use feet per minute because typical climb and descent rates produce sensible numbers — a commercial aircraft climbs at 1,500–2,500 ft/min, and descends at 300–500 ft/min for approach. In ft/s these would be 25–42 and 5–8 respectively — workable, but ft/min produces rounder pilot-friendly numbers for the ranges encountered.

Foot per second squared (ft/s²) is the imperial unit of acceleration. Standard gravitational acceleration is 32.174 ft/s² — meaning a falling object gains 32 ft/s of speed every second. This is used in US aerospace and artillery calculations. Engineers must be careful not to confuse ft/s (speed) with ft/s² (acceleration), as the units look similar but represent entirely different physical quantities.

One knot is approximately 1.6878 ft/s (or 1 nautical mile per hour). This means 100 knots is about 169 ft/s. Aircraft airspeed is measured in knots by international convention, but US military aircraft radar tracks and some engineering documents also express speeds in ft/s for compatibility with imperial-unit weapon system specifications.