Consider a satellite moving very close to the Earth’s surface in a circular path.
PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
Consider a satellite moving very close to the Earth’s surface in a circular path.
(i) Starting from the general expression for orbital speed obtained from fundamental laws, show that for an orbit where the altitude h is negligible compared to the Earth’s radius RE, the speed can be written as v=gRE, where g is the acceleration due to gravity at the surface.
(ii) Using g=9.8ms−2 and RE=6.37×106m, evaluate the speed numerically.
(iii) Hence find the minimum horizontal speed that must be imparted to a projectile at the Earth’s surface so that it just enters such a circular orbit, assuming no air resistance.