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183_notes:curving_motion [2015/09/27 15:49] – [Relationship to the tangential and centripetal accelerations] caballero | 183_notes:curving_motion [2021/03/04 12:56] (current) – [Modeling Curved Motion] stumptyl |
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| Section 5.5, 5.6 and 5.7 in Matter and Interactions (4th edition) |
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===== Modeling Curved Motion ===== | ===== Modeling Curved Motion ===== |
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The motion of objects is not limited to [[183_notes:displacement_and_velocity|straight line motion]]. As you read earlier, [[183_notes:momentum_principle|forces can change the momentum of objects]] (including the direction of that momentum). These interactions can produce [[183_notes:localg|projectile motion]], [[183_notes:ucm|circular motion]], [[183_notes:springmotion|oscillations]], or more generalized trajectories. In these notes, you will read about how to model more generalized motion using the [[183_notes:momentum_principle|momentum principle]]. | The motion of objects is not limited to [[183_notes:displacement_and_velocity|straight line motion]]. As you read earlier, [[183_notes:momentum_principle|forces can change the momentum of objects]] (including the direction of that momentum). These interactions can produce [[183_notes:localg|projectile motion]], [[183_notes:ucm|circular motion]], [[183_notes:springmotion|oscillations]], or more generalized trajectories. **In these notes, you will read about how to model more generalized motion using the [[183_notes:momentum_principle|momentum principle]].** |
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==== Lecture Video ==== | ==== Lecture Video ==== |
$$\vec{F}_{\parallel} = m\vec{a}_{t} = m{a}_{t}\hat{p} \qquad \vec{F}_{\perp} = m\vec{a}_{c} = m{a}_{c}\hat{n}$$ | $$\vec{F}_{\parallel} = m\vec{a}_{t} = m{a}_{t}\hat{p} \qquad \vec{F}_{\perp} = m\vec{a}_{c} = m{a}_{c}\hat{n}$$ |
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The direction of each of these accelerations is the same as their corresponding forces. The tangential acceleration is tangent to the path, and this points in the $\hat{p}$ direction. The centripetal acceleration is perpendicular to the path and points in the $\hat{n}$ direction. You can use the magnitudes of each force component to determine formulae for the accelerations. | The direction of each of these accelerations is the same as their corresponding forces. The tangential acceleration is tangent to the path, and this points in the $\hat{p}$ direction (or opposite it in the case of negative acceleration). The centripetal acceleration is perpendicular to the path and points in the $\hat{n}$ direction. You can use the magnitudes of each force component to determine formulae for the accelerations. |
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$$F_{\parallel} = m{a}_{t} = \dfrac{d|\vec{p}|}{dt} = \dfrac{d|m\vec{v}|}{dt} = m\dfrac{d|\vec{v}|}{dt} \qquad\longrightarrow\qquad {a}_{t} = \dfrac{d|\vec{v}|}{dt}$$ | $$F_{\parallel} = m{a}_{t} = \dfrac{d|\vec{p}|}{dt} = \dfrac{d|m\vec{v}|}{dt} = m\dfrac{d|\vec{v}|}{dt} \qquad\longrightarrow\qquad {a}_{t} = \dfrac{d|\vec{v}|}{dt}$$ |
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The centripetal acceleration tells you how the direction of the object's motion changes, just as the perpendicular component of the net force is responsible for this directional change. | The centripetal acceleration tells you how the direction of the object's motion changes, just as the perpendicular component of the net force is responsible for this directional change. |
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| ==== Video of Bowling Ball Moving in a Circle ==== |
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| In this video a bowling ball is forced to move in a circle by being struck with a sledgehammer. This video was originally collected by [[http://paer.rutgers.edu|Eugenia Etkina and David Brookes]]. |
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| {{183_notes:bowlingball.mp4}} |
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| ==== Examples ==== |
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| * [[:183_notes:examples:videoswk6|Video Example: Change in momentum (parallel and perpendicular) of an orbit]] |