given that the radius of the earth is 6.37×10^3km and the period of revolution of the moon round the earth is 27.3 days, calculate the average distance from the earth to the moon.

1 answer

Well, you know the Gravitational Field Strength at Earth's surface, 9.8N/kg, and that this is reduced by distance squared, so at the moons location, it is...

field strength= 9.8N/kg * (re/d)^2 where re is the radius of Earth, and d is the distance from the EArth cneter to the Moon center.

This field strength is also equal to the acceleration falling toward EArth, so at the moon...

9.8(re/d)^2=V^2/d=(2PId/period)^2/d

9.8 re^2=4PI^2 d^3/period

Solve for d change period in days to seconds first, and re to meters