Respuesta :
There is a gravitational force pulling the stack of books downward. Gravity is always a factor on earth. Keep that in mind when asked these sort of questions. They are made to confuse you. Take your time and you will do just fine.
There is a gravitational force pulling the stack of books downward. Gravity is always a factor on earth. Keep that in mind when asked these sort of questions. They are made to confuse you. Take your time and you will do just fine.