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Frequently Asked Questions
How do I convert mph to km/h?
Multiply mph by 1.60934. Example: 60 mph = 60 × 1.60934 = 96.56 km/h. Quick estimate: multiply by 1.6. To go the other way: multiply km/h by 0.621371.
What is a knot in mph?
1 knot = 1 nautical mile per hour = 1.15078 mph = 1.852 km/h. Knots are used in aviation and maritime navigation. Wind speed in weather reports is often given in knots.
How fast is Mach 1?
Mach 1 is the speed of sound — approximately 343 m/s (1,235 km/h or 767 mph) at sea level at 20°C. The speed of sound varies with temperature and altitude: it's slower at higher altitudes where air is colder and thinner.
What is the speed of light?
The speed of light in a vacuum is exactly 299,792,458 metres per second (approximately 300,000 km/s or 186,000 miles/second). Nothing with mass can reach or exceed this speed.