Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
Moving in Circles
What forces are
on you when
you go around
a corner?
Task
• Try and explain why a car skids when it goes
around a corner too quickly.
Learning objectives
• How can we recognise uniform motion in a
circle?
• What do we need to measure to find the
speed of a...
Objects which move in a circular path
any suggestions?
The hammer swung by a hammer thrower
Clothes being dried in a spin ...
The Wheel
The speed of the perimeter of each wheel is
the same as the cyclists speed, provide
that the wheel does not slip...
Angular displacement
The big wheel has a diameter of 130m and a full
rotation takes 30 minutes (1800 seconds)
3600
/ 1800 ...
Angular displacement
The big wheel has a diameter of 130m and a full
rotation takes 30 minutes (1800 seconds)
3600
/ 1800 ...
Upcoming SlideShare
Loading in …5
×

Moving in circles

536 views

Published on

How can we recognise uniform motion in a circle?
What do we need to measure to find the speed of an object moving in uniform circular motion?
What is meant by angular displacement and angular speed?

Published in: Education, Business, Technology
  • Be the first to comment

  • Be the first to like this

Moving in circles

  1. 1. Moving in Circles What forces are on you when you go around a corner?
  2. 2. Task • Try and explain why a car skids when it goes around a corner too quickly.
  3. 3. Learning objectives • How can we recognise uniform motion in a circle? • What do we need to measure to find the speed of an object moving in uniform circular motion? • What is meant by angular displacement and angular speed?
  4. 4. Objects which move in a circular path any suggestions? The hammer swung by a hammer thrower Clothes being dried in a spin drier Chemicals being separated in a centrifuge Cornering in a car or on a bike A stone being whirled round on a string A plane looping the loop A DVD, CD or record spinning on its turntable Satellites moving in orbits around the Earth A planet orbiting the Sun (almost circular orbit for many) Many fairground rides An electron in orbit about a nucleus
  5. 5. The Wheel The speed of the perimeter of each wheel is the same as the cyclists speed, provide that the wheel does not slip or skid. r If the cyclists speed remains constant, his wheels turn at a steady rate. An object turning at a steady rate is said to be in uniform circular motion The circumference of the wheel = 2 π r The frequency of rotation f = 1/T, T is the time for 1 rotation The speed v of a point on the perimeter = circumference/ time for 1 rotation V = (2 π r) / T = 2 π r f Worked example p22
  6. 6. Angular displacement The big wheel has a diameter of 130m and a full rotation takes 30 minutes (1800 seconds) 3600 / 1800 = 0.20 per second (2π radians) 20 in 10 seconds 200 in 100 seconds (π/18 radians) 900 in 450 seconds (π/2 radians) The wheel will turn through an angle of (2 π/T) radians per second T is the time for one complete rotation The angular displacement (in radians) of the object in time t is therefore = 2 π t T = 2 π f t The angular speed (w) is defined as the angular displacement / time w = 2 π f w is measured in radians per second (rad s-1 )
  7. 7. Angular displacement The big wheel has a diameter of 130m and a full rotation takes 30 minutes (1800 seconds) 3600 / 1800 = 0.20 per second (2π radians) 20 in 10 seconds 200 in 100 seconds (π/18 radians) 900 in 450 seconds (π/2 radians) The wheel will turn through an angle of (2 π/T) radians per second T is the time for one complete rotation The angular displacement (in radians) of the object in time t is therefore = 2 π t T = 2 π f t The angular speed (w) is defined as the angular displacement / time w = 2 π f w is measured in radians per second (rad s-1 )

×