Lesson 4: Newtons Law of Equal and Opposite Reactions, the Third Law!

Think about jumping. If you push down on the Earth with a force of 1000 N, the Earth pushes back on you with a force of 1000 N, and you jump up.

Look at the image of the student. The arrow pointing down shows the gravitational force applied to the student. This is the student's weight. The arrow pointing up shows the normal force from the ground. It is equal and opposite to the gravitational force.

You might ask: "When you push down on the Earth, why doesn't the Earth move?" The Earth does move a little bit, but not enough to notice. This is because Earth's mass is huge, so its acceleration (from Newton's second law) is very small. It would take a force trillions of times more than your weight to see a real change in Earth's acceleration.

Add information about Newton's Third Law of Motion to your concept map.