The gravity of an object depends on its size. Air pressure and altitude. The motion under gravity refers to the movement of an object whose vertical motion is affected by the presence of gravity. In this situation, there was clearly an unknown force at play, that force is what Newton called gravity and his theory is called Newton’s law of Universal Gravitation. The gravitational force on the moon is around 16% of that on Earth, Mars has around 38% of the Earth’s pull and Jupiter has 2.5 times the Earth’s gravity. Tides and planetary orbits are caused by the pull of gravity. So, if gravity pulls everything down, then why don't things on the bottom of the Earth get pulled down into space? 2. Deependra Misra. includes; plugin-and-theme-hooks; class-gravityview-plugin-hooks-gravity-forms-signature.php. It is the force that pulls on all of the mass in your body. Anything which has mass also has a gravitational pull. As a result it has less gravity. 1