# Velocity

Velocity is a vector quantity that specifies the time rate of change of displacement with respect to a reference frame. If the reference frame is not inertial, the velocity is often designated "relative velocity".

 1 mph = 1.609 km/h 1 ms-1 = 3.2808399 fts-1 1 in s-1 = 0.0254 ms-1 1 ft s-1 = 0.3048 ms-1 1 km h-1 = 0.2778 ms-1 1 ft min-1 = 0.00508 ms-1 1 knot = 0.5144 ms-1

1km h-1 = 1 km/h = 1000 m/h = 1000/3600 m/s = 0.2778m/s

Note: if using this type of conversion within a calculation then best to use 1000/3600 in the calculation rather than the value round to 4 decimal points.

 Snail 0.013 ms-1 Fast walk 1.79 ms-1 (4 mph) Stephenson′s Rocket 13.4 ms-1 (30 mph) Steam train speed record 56.3 ms-1 (126 mph) Fastest boat (Spirit of Australia 1978) 141.95 ms-1 (317.6 mph) Land speed record (Thrust SSC 1997) 341.0 ms-1 (763 mph) Concorde 597 ms-1 (1336 mph) Fastest plane (SR71 BlackBird) 980 ms-1 (2193 mph) Escape velocity at surface of the Moon 2.38x103 ms-1 Escape velocity at surface of the Earth 1.12x104 ms-1 Escape velocity at surface of the Sun 6.18x105 ms-1 Speed of light in vacuo 2.998x108 ms-1

### Acknowledgement

We would like to thank Peter W Kruhøffer for pointing out the error in our conversion table from km h-1 to ms-1

Subjects: Classical Mechanics