Foot per Hour to Foot per Second

Tectonic plates move at 2–15 cm/year on average — far below even 1 ft/h. However, during episodic "slow-slip events" on faults (a kind of slow-motion earthquake), the fault face can creep at detectable rates closer to mm/day. True ft/h movement would be catastrophic — the San Andreas Fault creeping at 1 ft/h would translate to 2.4 miles/day, far exceeding any measured geological rate.

Metal extrusion (forming rods or tubes by forcing material through a die) often runs at 1–100 ft/h depending on the alloy and die profile. Some ceramic and glass fiber drawing processes operate in this range. Paper mill wet-end press sections can be as slow as 10–50 ft/h during startup. These speeds are slow enough that workers can safely observe and adjust the process manually.

Icebergs drift with ocean currents at roughly 0.5–1 km/day, equivalent to about 55–110 ft/h. Calving glaciers can lurch forward at thousands of ft/h during surge events. The famous 2017 calving of iceberg A-68 from the Larsen C ice shelf happened over a period of days — so its "speed" of separation was only a few ft/h at most.

It depends on the magnitude. 1 ft/h = 24 ft/day = 288 in/day — for something moving a few feet per hour, inches per day becomes a large awkward number. Conversely, for very slow movement (0.01 ft/h = 2.88 in/day), in/day gives a cleaner number. Engineers choose whichever unit gives a value between roughly 1 and 1,000 to minimize leading zeros.

Sea stars (starfish) move at roughly 0.06 m/min, which is about 11.8 ft/h — surprisingly fast. Coral polyps and sea anemones are essentially sessile but can contract at a few mm/min. Some fungi extend their hyphal tips at 1–4 mm/h — about 0.003–0.013 ft/h. Slime molds (Physarum polycephalum), often used in computing research, can advance at up to 4 cm/h (about 1.3 ft/h).

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.