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  2. Speed of sound - Wikipedia

    en.wikipedia.org/wiki/Speed_of_sound

    The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. More simply, the speed of sound is how fast vibrations travel. At 20 °C (68 °F), the speed of sound in air, is about 343 m/s (1,125 ft/s; 1,235 km/h; 767 mph; 667 kn), or 1 km in 2.91 s or one mile in 4.69 s.

  3. Beaufort scale - Wikipedia

    en.wikipedia.org/wiki/Beaufort_scale

    < 1 mph < 1 km/h 0–0.2 m/s: 0 ft 0 m Sea like a mirror Smoke rises vertically 1 Light air 1–3 knots 1–3 mph 1–5 km/h 0.3–1.5 m/s 0–1 ft 0–0.3 m Ripples with appearance of scales are formed, without foam crests Direction shown by smoke drift but not by wind vanes 2 Light breeze 4–6 knots 4–7 mph 6–11 km/h 1.6–3.3 m/s

  4. Hull speed - Wikipedia

    en.wikipedia.org/wiki/Hull_speed

    Hull speed or displacement speed is the speed at which the wavelength of a vessel's bow wave is equal to the waterline length of the vessel. As boat speed increases from rest, the wavelength of the bow wave increases, and usually its crest-to-trough dimension (height) increases as well. When hull speed is exceeded, a vessel in displacement mode ...

  5. Newton-second - Wikipedia

    en.wikipedia.org/wiki/Newton-second

    (m/s) Momentum (N⋅s) Explanation 0.42 2.4 1 A 420-gram (15 oz) football (FIFA specified weight for outdoor size 5) kicked to a speed of 8.6 km/h (5.3 mph). 0.42 38 16 The momentum of the famous football kick of the Brazilian player Roberto Carlos in the match against France in 1997. The football had a speed of 137 km/h (85 mph), making it one ...

  6. Orders of magnitude (length) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(length)

    111 kmdistance covered by one degree of latitude on Earth's surface; 120 km – width of Brunei; 180 kmdistance between Mumbai and Nashik; 200 km – width of Qatar; 203 km – length of Sognefjorden, the third-largest fjord in the world; 220 kmdistance between Pune and Nashik; 240 km – width of Rwanda

  7. Doppler effect - Wikipedia

    en.wikipedia.org/wiki/Doppler_effect

    If the wave is a sound wave and the sound source is moving faster than the speed of sound, the resulting shock wave creates a sonic boom. Lord Rayleigh predicted the following effect in his classic book on sound: if the observer were moving from the (stationary) source at twice the speed of sound, a musical piece previously emitted by that ...

  8. Naismith's rule - Wikipedia

    en.wikipedia.org/wiki/Naismith's_rule

    The original Naismith's rule from 1892 says that one should allow one hour per three miles on the map and an additional hour per 2000 feet of ascent. [1] [4] It is included in the last sentence of his report from a trip. [1] [8] Today it is formulated in many ways. Naismith's 1 h / 3 mi + 1 h / 2000 ft can be replaced by:

  9. Pace (unit) - Wikipedia

    en.wikipedia.org/wiki/Pace_(unit)

    A pace is a unit of length consisting either of one normal walking step (approximately 0.75 metres or 30 inches), or of a double step, returning to the same foot (approximately 1.5 metres or 60 inches).