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This lesson reviews different types of forces and how to draw free body diagrams to represent the forces on an object.

- Introduction to free body diagramsGet 3 of 4 questions to level up!

Newton's first law, also called the law of inertia, says that there must be a net external force on an object for there to be any change in velocity.

Newton's second law tells us how much an object will accelerate for a given net force.

Newton's third law says that forces always occur in pairs. For example, if the Earth is pulling down on you, you are also pulling up on the Earth with a force of equal magnitude and opposite direction.

- Identifying equal and opposite forcesGet 3 of 4 questions to level up!

Sometimes forces are applied at an angle. We can use trigonometry to separately analyze the force components along the coordinate axes.

- Forces at an angleGet 3 of 4 questions to level up!

What forces are acting on you when you slide down a frictionless ramp? In this lesson we'll learn how to analyze the motion of an object on an inclined plane.

- Forces and inclined planesGet 3 of 4 questions to level up!

What keeps a parked car from sliding down a slope? This lesson looks at what happens when we include static and kinetic friction forces between two objects.

- Static and kinetic frictionGet 3 of 4 questions to level up!

Up next for you:#### Unit test

Level up on all the skills in this unit and collect up to 700 Mastery points!AP® is a registered trademark of the College Board, which has not reviewed this resource.