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18 Cards in this Set
- Front
- Back
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axle
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shaft on which a wheel rotates
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axis of rotation
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imaginary line that passes through the centre of rotation perpendicular to the circular motion
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uniform circular motion
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motion in a circular path at a constant speed*
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can an object have a constant speed and changing velocity? constant velocity and changing speed?
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1. Yes. Even if the speed is constant, if the direction that the object is travelling at is changing, there is a changing velocity. - THIS MEANS THAT OBJECTS TRAVELLING IN A CIRCLE ARE ALWAYS ACCELERATING.
2. No. Since speed is a factor of velocity, then if the speed is changing so must the velocity. |
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centripetal acceleration
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- direction of centripetal acceleration is towards the CENTRE of the circle
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centripetal net forces
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- direction of the net force is towards the centre of the circle
Fnet = mac Fnet = mv2/r Fnet = m4pi2r/T2 |
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centrifugal force
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a fictitious force that pulls us outwards when travelling in circles. This occurs due to inertia, as there is no real force pulling us outward.
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cycle
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one complete back and forth motion or oscillation
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revolution
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one complete cycle for an object moving in a circular path
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period
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time required for an object to make an oscillation.
short hand "T" measure in seconds (s) |
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frequency
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number of cycles or oscillations per second
measured in Hertz symbolized "f" |
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rpms
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revolutions per minute
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single force problems
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- when only one force accounts for the centripetal motion of the object (when the object is circulating horizontally)
- Fnet = Fapp |
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vertical loop problems
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- objects are travelling on a vertical plane
- affected by the force of gravity as well as the applied force Fnet = Fapp + Fg top of loop... Fnet = Fapp + Fg bottom of loop.. Fnet = Fapp - Fg |
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Kepler's 3 Laws of Planetary Motion
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1. the path of planets are ellipses with the sun's centre acting as one focus
2. an imaginary line from the sun sweeps out equal areas in equal time intervals. Therefore; planets move fastest when closest to the sun, and slowest when further away. 3. relationship between the periods and the distances from the sun for any two satellites can be expressed as T2/R3 = T2/R3 |
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satellite
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an object in a state of free fall as it circles the earth. to launch a satellite from Earth, it must be launched at 8km/s.
*the mass of the satellite is not important when launching, as it is not a part of the satellite equation! |
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geostationary satellite
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geostationary/geosynchronous satellites maintain a fixed position above the Earth's surface.
Therefore, their period match the rotation of the Earth (T = 24.0 hours) |
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weight and weightlessness
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*astronauts are not truly weightless as they orbit the Earth in the shuttle. They are merely falling at the same rate as the shuttle, and appear to be weightless
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