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16 Cards in this Set
- Front
- Back
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states that forces always act in equal but opposite pairs |
Newton's third law of motion |
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what happens when one object exerts a force on another object |
the second object exerts the same size force on the first object |
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the forces exerted by two objects on each other |
action-reaction force pair |
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why don't action-reaction forces cancel out on each other |
they're action on different objects |
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why is it sometimes not easy to notice an action-reaction pair |
one of the objects is more massive and appears to lay motionless as an force acts on it |
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what is the action force of a rocket |
the downward push as the wall exerts a force that pushes the gas molecules out the bottom of the engine |
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what is the reaction force of a rocket |
the upward push on the rocket by the gas molecules |
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when measuring weight on a scale, what does the force balance |
the downward pull of gravity on you |
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when is a falling object in freeful |
when the only force acting on the object is gravity |
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the condition that occurs in free fall when the weight of an object seems to be zero |
weightlessness |
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are space shuttles in free fall |
yes |
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do space shuttles fall in a curved path around earth or fall straight downward |
curved path |
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what is the action and reaction force of a flying bird |
wings push downward and backward against air, so air pushes forward and upward against wings |
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can either force be the action or reaction force |
yes |
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in an action-reaction force, what do the accelerations of the objects depend on |
the mass |
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why do objects in orbit seem to be weightless |
they are in free fall in a curved path around earth |
