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Unit: Forces and Newton's laws of motion


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

Let's learn about what a force is and how Newton changed the world's view of how reality works.
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