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30 Cards in this Set
- Front
- Back
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Dynamics
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Connection between force and motion
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Force
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any kind of push or pull on an object, an action capable of accelerating an object
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Is force a vector?
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Yes, it has magnitude and direction
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If no force is applied to a moving object, it will ____
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continue to move with constant speed in a straight line
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An object slows down only if ___
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a force is exerted on it
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net force is zero
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when the vector sum of the two forces are in opposite directions
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Newton's first law of motion (law of inertia)
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Every object continues in its state of rest, or of uniform velocity in a straight line, as long as no net force acts on it
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Inertia
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The tendency of an object to maintain its state of rest or of uniform velocity in a straight line
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Inertial reference frames
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the law of inertia is valid in these reference frames
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mass (in terms of inertia)
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measure of inertia of a value
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Mass vs. weight
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Mass: property of an object itself, quantity of matter
Weight: is a force, the pull of gravity acting on an object |
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Direction of velocity changes when
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the net force acts sideways on a moving object
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Acceleration = change in velocity, so a net force causes ___
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a change in acceleration
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Newton's Second law of motion
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The acceleration of an object is directly proportional to the net force acting on it, and its inversely proportional to its mass. Direction of the acceleration is in the direction of the net force acting on the object
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Equation for Newton's Second Law
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ΣFnet = ma
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units of 1 N
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1kg * m/s^2
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1 dyne
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1 g * cm/s^2
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1 lb, unit of ___
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4.44822N, unit of force
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1 slug, unit of __
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1lb = 1 slug * ft/s^2, mass
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force is exerted __ an object and is exerted __ another object
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on, by
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Newton's Third Law of Motion
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Whenever one object exerts a force on a second object, the second object exerts an equal force in the opposite direction on the first
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Equation for Newton's Third Law
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Fpg = -Fpg
Fpg = force exerted on the person by the ground -: indicates the forces are in opposite directions |
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Gravitational Force
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Fg = mg
direction of force is down magnitude is often called weight |
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Contact Force
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the force exerted when two objects are in contact
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Normal Force
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perpendicular force to the common surface of contact
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net force
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vector sum of all forces acting on an object
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Free-body diagram
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shows all the forces acting on each object involved
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tension
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when a flexible cord pulls on an object
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Kinetic Friction
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sliding friction
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Static Friction
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force parallel to the two surfaces that can arise even when they are not sliding
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