Explain how Newton verified his law of gravitation.

Explanation

(i) Newton verified his law of universal gravitation by comparing the accelaration of a terrestrial object to the acceleration of the moon.
(ii) He knew that the distance from the centre of earth to the center of two spheres of known mass at either end of a light rod suspended by a then fiber from the center of the rod.
(iii) He had earlier found the small force that was needed to twist the fiber.
(iv) By brining a third sphere close to one of the suspended spheres.
(v) He was able to measure the force of gravity between the sphere and hence gravitation.