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Sir Isaac Newton. Force, Gravity, and Friction. Forces. Force – a push or pull on an object Contact force – push or pull on one object by another object that is touching it. Contact forces can be weak or strong: for example; (weak) press the k eys on a keyboard.
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Sir Isaac Newton Force, Gravity, and Friction
Forces • Force – a push or pull on an object • Contact force – push or pull on one object by another object that is touching it. Contact forces can be weak or strong: for example; (weak) press the keys on a keyboard. (strong) the force of the Earth’s plates pushing against one another to form mountains. • Noncontact force –the force that one object can apply to another without touching it. For example: gravity and magnetic force.
Law of Universal Gravitation • All objects are attracted to each other by a gravitational force. • The strength of the force depends on the mass of the object and the distance between them. • GF increases if the mass of at least one object increases • GF force between objects decreases as the objects move apart • (mass is the amount of matter in an object)
Friction • A force that resists the motion of two surfaces that are touching. • Fluid friction-is friction between a surface and a fluid • (fluid is any material that flows) for example: water and air are fluids • Fluid friction between air and a surface is air resistance
inertia • The tendency of an object to resist change in its motion • For example; the crash-test dummy: the car hits a wall, the car stops but the dummy keeps moving forward