Physics 10/13

Physics 10/13

Newton's 3rd Law

Open Ended

What do you think is meant by "interaction pairs"?

Interaction Pairs

• A set of two forces that are in opposite directions, have equal magnitudes, and act on different objects.

• F_{A on B} and the F_{B on A}

• Sometimes referred to as an action-reaction pair

Misconception

This might make it sound like on force causes the other, but this isn't true. The forces either exist together or not at all.

Newton's Third Law

You are probably familiar with for every action, there is an equal and opposite reaction, but let's simplify it. All forces come in pairs that act on different objects, are equal in strength, and act in opposite directions.

Newton's Third Law

The force of A on B is equal in magnitude an opposite in direction of the force of B on A.

F_{A on B} = -F_{B on A}

Fill in the Blanks

A softball has a mass of 0.18 kg, what is the gravitational force on Earth due to the ball an what is Earth's resulting acceleration? Earth's mass is 6.0 X 10²⁴ kg.

Open Ended

State Newton's Third Law of Motion