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41 Cards in this Set
- Front
- Back
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One radian
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The angle sub tended at the centre of a circle by an arc of length equal to the circle's radius.
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Convert radians to degrees...
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*(180/pi)
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Convert degrees to radians...
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*(pi/180)
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When does an object move with circular motion?
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When a force is acting on it perpendicular to the velocity.
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In what direction does centripetal acceleration act?
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Towards the centre of the circle.
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What is centripetal acceleration?
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It is the acceleration of a body moving in a circle with constant speed.
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Centripetal acceleration equation
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a=(v^(2))/r
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Speed equation for circular motion
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V=2pir/T
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Centripetal force equation
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F=mv^2/r
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What is a field?
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A field is a region within which a force operates.
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What type of field operates around any mass?
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Gravitational field
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What is gravitational field strength?
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The force acting per unit mass at a point.
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Gravitational field strength equation
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g=F/m
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How is the gravitational field of the Earth distributed close to the Earth's surface?
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Uniformly (g=9.81)
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Newton's law of gravitation (words)
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The gravitational force of attraction between two bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
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Newton's Law of Gravitation equation
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F=-GMm/r^2
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Gravitational field strength equation 2
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g= GM/r^2
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Define the period of a planet.
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The time it takes to complete one orbit around the Sun.
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State Kepler's third law
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The square of the period T of a planet is directly proportional to the cube of its distance r from the Sun.
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Kepler's third law equation
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T^2=(4pi^2r^3)/GM
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Derive Kepler's third law equation.
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Equate centripetal force and gravitational force equations. Substitute in v^2 from circular motion speed equation. Rearrange.
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For a satellite to be geostationary it must: (4 points)
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1. Have it orbit centred on the centre of the Earth.
2. Be travelling from West to East. 3. Be over the equator (equatorial orbit). 4. Have a period of 24 hours. |
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Uses of a geostationary satellite...
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Telecommunications and television broadcasting.
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Examples of free oscillations
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Banging a drum, knocking ink a door, hitting a nail with a hammer etc.
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Displacement
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The distance an object has moved from its mean, or rest, position.
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Amplitude
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The maximum displacement.
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Frequency
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The number of oscillations per unit time at any point.
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Period
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The time for one complete pattern of oscillation to take place at any point.
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Period T equation
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=1/f
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Define simple harmonic motion.
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An object undergoing simple harmonic motion has acceleration proportional to its displacement from a fixed point, where the acceleration acts in the opposite direction to the displacement. (Or always acts towards equilibrium position).
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Displacement equation (SHM)
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If x=0 when t=0:
x=Asin(2pift) If x=A when t=0 x=Acos(2pift) |
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Simple harmonic motion equation
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a=-((2pif)^2)x
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Displacement-time graph for SHM
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Sin graph max/min disp=A/-A
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Acceleration-time graph (SHM)
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Sin graph out of phase with displacement graph. Max/min acc = +-((2pif)^2)A
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Velocity-time graph for SHM
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Cos graph max/min velocity= +-(2pif)A
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Maximum velocity equation (SHM)
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Vmax=2pifA
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For SHM how is the period affected by the amplitude?
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There is no effect. The period is independent of the amplitude for SHM.
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Energy change graph for SHM
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What is damping?
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Deliberately reducing the amplitude of an oscillation is called damping.
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Angular frequency equation
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w=2pif (rads^-1)
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Light damping
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Damping by small forces.
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