Forces and Motion

Broadening your horizons

Stories from Physics for 11-14 14-16 IOP RESOURCES

A straightforward geometrical calculation can determine an approximation for the distance to the horizon given an observer’s height above the surface of the Earth: d=  13H  km, where d is the distance to the horizon in km and H is the vertical height in metres of the observer above the ground. A person with their eyes 2 m above the ground will see the horizon at a distance of approximately 5 km. A further correction can be made to account for the deviation of the path of light due to refraction.


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