In Gravitation, Sir. Newton was able to prove the inverse square law but how he proved

but how he proved that Force is directly proportional to the product of masses

Dude, This link may help you





 

http://faculty.eicc.edu/tgibbons/pscrgravity.htm

THESE PROPORTIONALITIES ARE ACTUALLY EXPERIMENTAL. TO GET THE RELATIONS, EXPERIMENTS ARE DONE TO FIND THE VARIANCE IN ONE QUANTITY WITH RESPECT TO ANOTHER QUANTITY.



NEWTON PROBABLY PRESUMED THAT FORCE MUST BE DUE TO THERE MASS. INFACT IT MUST DEPEND ON BOTH BODY MASSES. HENCE FOR TAKING THE LCM OF BOTH, HE MULTIPLIED BOTH MASSES AND EXPERIMENTED ALOT TO FIND THAT PRODUCTS ARE DIRECTLY PROPORTIONAL. HENCE WE CAN ASSUME THAT ALL FACTS, FIRST CAME FROM MERE PREDICTIONS.



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