Forces change Motion

Force is a push or pull Types of force: Applied Force: Requires contact between objects, like pushing or pulling. Example: pushing a book across a table.

Act at a distance, such as gravity and electromagnetic forces. Friction is a force that acts in an opposite direction to the motion.

Frictional Force Applied Force Magnetic Force Gravity Tension Force Buoyant Force Spring Force Drag Force

Size & Direction of Force Force has size & direction, like a vector. Shooting a basketball requires the right amount of force, and direction to get it in the hoop.

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Net Force: Total force that affects an object when multiple forces are combined, like an addition problem.

Balanced forces have same effect as no force at all. Example: Tug of war when the teams pulling on the rope are applying an equal force, the rope does not move.

Unbalanced forces change the motion of an object. Example: Tug of war when one team is applying a larger force then the other, an unbalanced force occurs and the rope moves (Like when the teachers pulled you down in the Pep Rally)

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Newton’s 1st law of motion An object at rest stays at rest and an object in motion stays in motion at the same speed and in the same direction, unless acted on by an unbalanced force. What types of forces on Earth make objects in motion slow down? ________________

Newton’s 1st law of motion Objects with no net force have constant or zero velocity. Force is needed to start or change motion

Inertia: resistance of an object to a change in speed or direction of motion It is more difficult to change the motion of an object that has more mass. When you measure mass of an object, you are also measuring inertia.

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Newton’s 2nd law of motion Acceleration is produced when a force acts on a mass. F = ma; “F” is Force, “m” is mass, and “a” is acceleration (speed).

Newton’s 3rd law of motion For every force, there is a reaction force of the same size in the opposite direction. Every act has an equal and opposite reaction.

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