What are action-reaction force pairs?

Ahypothesis is? close agreement by competent observers of observations of the same phenomena. a guess that has been tested over and over again and always found to be true. an educated guess that has yet to be proven by experiment. the long side of a right triangle. a synthesis of a large collection of information that includes guesses.

What tightening torque should be used for a hexagonal head screw (not split-bolt) on a 250 kcmil conductor?

What is a neurotransmitter involved in mood reward, addiction, and motor behaviors?