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Special relativity. The speed of light in vacuum, commonly denoted c, is a universal physical constant that is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour).
A light-minute is 60 light-seconds, and so the average distance between Earth and the Sun is 8.317 light-minutes. The average distance between Pluto and the Sun (34.72 AU [5]) is 4.81 light-hours. [6] Humanity's most distant artificial object, Voyager 1, has an interstellar velocity of 3.57 AU per year, [7] or 29.7 light-minutes per year. [8]
In 2005, the average marathon time in the U.S. was 4 hours 32 minutes 8 seconds for men, 5 hours 6 minutes 8 seconds for women. [165] In 2015, the men's and women's median marathon times were 4 hours 20 minutes 13 seconds and 4 hours 45 minutes 30 seconds respectively. [166] A goal many runners aim for is to break certain time barriers.
Preferred walking speed. The preferred walking speed is the speed at which humans or animals choose to walk. Many people tend to walk at about 1.42 metres per second (5.1 km/h; 3.2 mph; 4.7 ft/s). [1][2][3] Individuals may find slower or faster speeds uncomfortable. Horses have also demonstrated normal, narrow distributions of preferred walking ...
To complete training and as part of an annual test of their fitness, legionnaires must complete the 8 kilometres TAP ("Paratroopers 8 kilometer") of 8 kilometers (5 mi) loaded with rifle, helmet and a 12 kilograms (26 lb) pack in under 40 minutes, and a night march of 25 kilometers (16 mi) in three hours with a load of 18 kilograms (40 lb ...
4.04 × 10 −8 ly: Reflected sunlight from the Moon's surface takes 1.2–1.3 seconds to travel the distance to the Earth's surface (travelling roughly 350 000 to 400 000 kilometres). 10 −6: 1.58 × 10 −5 ly: One astronomical unit (the distance from the Sun to the Earth). It takes approximately 499 seconds (8.32 minutes) for light to ...
Although the division of hours into minutes and seconds did not occur until the Middle Ages, Classical astrologers had a minuta equal to 1 ⁄ 60 of a day (24 modern minutes), a secunda equal to 1 ⁄ 3600 of a day (24 modern seconds), and a tertia equal to 1 ⁄ 216,000 of a day (0.4 modern seconds).
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.