Constants Part A Communications satelitos are used to bounce radio waves from th

Question

Constants Part A Communications satelitos are used to bounce radio waves from the earth's surface to send messages around the curvature of the earth. In order to be available all the time, they must remain above the same point on the earth's surface and must move in a circle above the equator How long must it take for a communications satelite to make one complete crbit around the earth? (Such an orbit is said to be hours Submit Request Answer Part B Apply Newton's second law to the satelite and find its altitude above the earth's surface kn Submit Request Answer

Explanation / Answer

(a)

Time taken by satellite to make one complete orbit around the earth,

t = 24 hrs

t = 24*3600 s

t = 86400 s

(b)

Gravitational force on satellite,

Fg = GMm / R^2

Centripetal force, Fc = mv^2 / R

Balance the forces,

GMm / R^2 = mv^2 / R

where v = 2*pi*R / t

GM = R*(2*pi*R / t)^2

R^3 = GMt^2 / 4*pi^2

R = [6.67*10-11 * 6*1024 * 864002 / 4*3.142]1/3

R = 42265 km

Altitude above the earth's surface,

h = R - Re

h = 42265 - 6371

h = 35894 km

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