What causes a star to shine brightly

Automobile fuel efficiency is often measured in miles that the car can be driven per gallon of fuel (mpg). heavier cars tend to have lower fuel efficiencies (lower mpg ratings). which variable (weight or fuel efficiency) is most naturally considered the explanatory (predictor) variable in this context?

Which bonds are found inside a water molecule

What is the force that opposes motion and works against the downward pull? a) friction b) gravity c) weight d) acceleration