# Circular Motion Unit 1 Mod. 1 A2 OCR

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• Circular Motion
• Distance of one complete 'travel' around circle
• 2?r
• Circumference of circle
• Orbital Speed
• s = d/t
• d = 2?r
• 2?r = distance (around circle)
• v = 2?r/t
• s = v
• v = velocity
• v = 2?r/t
• t = t
• t = time taken for travel
• Angular Speed
• Ø = x/r
• Remember: 2? = 360°
• Angular speed - w
• w - omega   (a little bit curvier in handwriting)
• w = 2?/t
• "Amount of turn/ distance" per second - hence speed
• Simplifies to
• v = wr
• Proof
• v = 2?r/t
• Orbital Speed
• w = 2?/t
• "plugging in" w = 2?/t to     v = 2?r/t
• v = wr
• w = 2?/ T
• Derived from
• f = w/2?
• 1/f = 2?/w
• T = 2?/w
• Rearranges to...
• w = 2?/T
• Frequency
• f = w/2?
• f = frequency
• w = angular speed
• 2? = distance around whole circle
• Period
• TIME for ONE COMPLETE CYCLE
• T = 1/f
• Same as waves at   AS - level
• Centripetal Acceleration
• dØ = dx/r
• Just the radian "rule" don't worry!
• v = dx/dt
• IMPORTANT:  Only applies when dØ is VERY SMALL
• a = v^2/r
• a = w^2/r
• Centripetal Force
• F = mv^2/r