How is the mass of the Earth determined?
How is the mass of the Earth determined? Newton, Galileo, Henry Cavendish, and Eratosthenes contributed to this amazing calculation. • This calculation is done using Newton’s Law of Gravity, which formulates the attractive force (gravitational force) that two masses exert on each other: F=GmM/r2 In Newton’s equation, F is the gravitational force, G is a constant of proportionality, M and m are the two masses exerting the forces, and r is the distance between the two objects. • G was calculated by Henry Cavendish in 1798, and was determined to be 6.67 x 10-11 m3/(kg sec2). • Also needed is Newton’s second law of motion, F=ma, where F is the force applied to an object, m is the mass of the object, and a is its acceleration due to the force. • Galileo determined that the acceleration due to the force of gravity of Earth was a constant equal to 9.8 m/sec2 near the surface of the Earth. • Lastly, you need to know the radius of the Earth; this was first calculated by the Greek Eratosthenes t
