Use the universal law of gravitation, insert the known value for the gravitational constant, and use the fact that each kilogram is attracted by a force of 9.8 Newton.
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if g=9.8m/s, G=6.7*10-11Nm2kg-2,calculate the mass of earth, if the radius of the earth is approximately 64m
On Earth, 75 kilograms of mass weighs 165.35 pounds. That's quite a hound!
(all figures approximate)Mass of earth = 5.97 * 1024 kilogramsRadius of earth = 6.371 * 106 metresVolume of earth = 4/3 * pi * radius3 = 1.0832 * 1021 cu metresSo:(average) density = mass / volume = 5,510 kgs / cu metre
You multiply the mass by the gravity. Normal Earth gravity is about 9.8 (in meters/second2, or the equivalent newton/kilogram).
Density = mass / volume since earth is nearly spherical, Volume = (4/3)pi x r3 find volume, then divide this into the mass.