Which of the filling is a fossil fuel?

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

How are the crust and the inner core alike? a) they are both solid. b) they both have the same temperature. c) they are both under the same pressure. d) they are both very close to the center of the earth.

What does si stand for,when referring to a system of measurement