What is one of the main characteristics of a simple machine

Select the word from the list that best fits the definition classification of most stars on the h-r diagram

Which statement is true? a. kepler's laws apply only to the motion of earth. b. kepler's laws can be used to predict eclipses. c. kepler's laws are true for a central force that is directly proportional to distance. d. kepler's laws can be deduced from newton's laws of motion and gravity.

In the first law of thermodynamics, triangle e=q-w, what does q stand for