He constructed astrolabe and and sextant in order to observed the motion of the solar system. 

He recognized that the apple fell straight down because Earth attracted it. He wondered whether this force might extend beyond the trees to the clouds, to the moon, and even beyond.

He invented the apparatus used to measure the gravitational force between two objects'

He was convinced that geometry and mathematics could be used to explain the number, distance, and motion of the planets.

What was the value of the universal gravitation constant(G)?

According to the law of universal gravitation, the force is directly proportional to the distance.

What is the acronym of GPS

He proposed that gravity is not a force, but an effect of space itself.

Einstein’s theory, called the ___________________, makes many predictions about how massive objects affect one another. In every test conducted to date, Einstein’s theory has been shown to give the correct results.

If your mass here, in the earth is 58 kg, what would be your mass in the moon?