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Published byTiffany Marshall Modified over 8 years ago
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Uniform circular motion Purpose: Determine how the linear speed of an object in uniform circular motion depends on the: 1) radius of path 2) centripetal force Procedure:horizontal spin good period value one value held constant
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Uniform circular motion Lab analysis (on whiteboard): graph(s) relationship slope unit equation slope meaning y-intercept meaning general equation
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Uniform circular motion (UCM) Constant linear speed (v) Constant radius
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Uniform circular motion (UCM) Velocity is tangent to the circular path
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Uniform circular motion (UCM) Velocity is tangent to the circular path v v v v
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Uniform circular motion (UCM) Constant linear speed (v) Constant radius Changing direction changing velocity acceleration
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Uniform circular motion (UCM) Centripetal Acceleration: Change of velocity direction, not speed Toward radius, perpendicular to velocity Acceleration caused by ????????????? v v v v acac acac acac acac
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Uniform circular motion (UCM) Centripetal Acceleration: Change of velocity direction, not speed Toward radius, perpendicular to velocity Acceleration caused by unbalanced force v v v v acac acac acac acac
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Uniform circular motion (UCM) Centripetal force: net force along the radius that causes the circular motionF c = ΣF points toward center caused by other forces (F T, F g, F f, F N ) v v v v FcFc FcFc FcFc FcFc
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Uniform circular motion (UCM) Centripetal Acceleration: Change of velocity direction, not speed Same relationship with net force as before Same direction a c = ΣF / m a c = F c / m F c = m·a c v v v v acac acac acac acac
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Uniform circular motion (UCM) Centripetal Acceleration: Change of velocity direction, not speed Same relationship with net force as before Same direction a c = ΣF / m a c = F c / m F c = m·a c v v v v FcFc FcFc FcFc FcFc
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Uniform circular motion (UCM) Constant linear speed (v) Constant radius Changing direction changing velocity acceleration Linear speed – (distance) / (time) (Circumference) / (time) v = (2·π·R) / T Period (T) – time for one complete cycle (rotation)
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Linear speed vs. Rotational speed Rotational speed: Known as frequency – how often an event occurs f = (# rotations) / (time) unit:cycles / second = Hertz (Hz) T = (time) / (rotation) unit:seconds / cycle (seconds) f = 1 / TT = 1 / f
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Linear speed vs. Rotational speed Linear speed: (distance traveled) / (time) unit:m/s (mph, km/hr, etc.) Rotational speed: (# rotations) / (time) unit:cycles / second = Hertz (Hz) (rpm, rad/sec, etc.)
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Linear speed vs. Rotational speed Merry-Go-Round example Who has: greater linear speed? AB
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Linear speed vs. Rotational speed Merry-Go-Round example Who has: greater linear speed? A > B (more distance, same time) AB
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Linear speed vs. Rotational speed Merry-Go-Round example Who has: greater linear speed? A > B (more distance, same time) greater rotational speed? AB
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Linear speed vs. Rotational speed Merry-Go-Round example Who has: greater linear speed? A > B (more distance, same time) greater rotational speed? A = B (same rotations made each time) AB
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