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3.4 Newtons Third Law of Motion

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Another way to illustrate Newtons Third Law is to consider a person standing on a skateboard: As the person pushes off the skateboard in one direction, the skateboard will accelerate in the opposite direction. Action Force Person pushing the skateboard backwards. FBD of skateboard. Reaction Force Skateboard pushing the person forward. FBD of person.

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3.4 Newtons Third Law of Motion It is important to note that the action and reaction forces occur simultaneously, and always act on different objects. When applying Newtons Third Law, the action and reaction forces are shown on separate FBDs. The forces do not cancel each other out, and they are not added together.

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3.4 Newtons Third Law of Motion Explain each event in terms of Newtons Third Law: a)A rocket accelerates upwards off a launch pad. b)A swimmer moves through the water. c)A small balloon releases air and flies around the room. d)You are walking across the floor. SP # 1 p.139

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3.4 Homework Practice # 1-4 p.140 Questions # 1, 3-5, 7, 9 p.141