What was sir isaac doing when an apple fell on his head which would eventually lead to the theory of gravity?

Issac fell on his head besides a tree and discovered Gravity!

Some connecting rods have to lubricate the cylinder wall or piston pin. the answer is letter d. graphite coating can be a major  additive to many  coating  systems and things such as connecting rods.  it functions as a refractory, lubricant, thermal conductor, and electrical conductor for a machine or thing to enhance its work.

Geographic information system
global positioning system
one has the word information, the other has the word positioning