No force is necessary to a. start an object moving.
b. stop an object from moving.
c. cause a change in the motion of an object.
d. keep an object doing what it is already doing.

Several mountains together form a mountain . a few of these combined form a mountain system. several systems combined form a mountain , which can stretch thousands of miles in length.

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?

When a light bulb shines, it gives off light energy and energy. a. heat b. potential c. chemical d. electrical