Study

B2.1.2 - B2.1.4

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  • what does static friction relate to?
    refers to the force acting between two surfaces that are not moving relative to each other
  • What factors influence amount of friction in sport?
    nature of footwear and the surfaces , reaction forces - e.g weight
  • What is power?
    the rate at which work is performed - P = W/T or P = Fv
  • what is the equation for coefficient of restitution?
    relative velocity after collision / relative velocity before collision
  • what factors influence the coefficient of restitution?
    material of objects, height of drop
  • What does the coefficient of friction mean?
    nature of the 2 surfaces in contact with each other - how slippy or rough they are
  • Give an illegal use of CoR in sport
    Freezing of baseballs / bats CoR is limited
  • How is the CoR use controlled in sport - give an example
    New tennis / table tennis balls in matches; table tennis balls / basketball checked and must bounce to a certain height; golf club / baseball bats limit CoR
  • What is meant by Work?
    the application of force over a distance W=Fd
  • give a legal example of CoR use in sport
    squash ball warm up - ball travels faster when it is warm
  • What is Newton's 3rd law?
    Law of reaction - for every action there is an equal and opposite reaction
  • What sport would you want a high CoF and why?
    spikes / studs - increase grip
  • What is Newton's First Law?
    Law of inertia - an object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction, unless acted upon by an
  • What can dynamic/kinetic friction also produce?
    heat and sound
  • What is the equation for friction force?
    f = coefficient friction N (or R)
  • How can power output be optimised
    Technique and sports equipment design
  • Define friction
    “A force that acts parallel to the interface of two surfaces that are in contact, and opposes their relative motion”
  • What is dynamic/kinetic friction?
    the frictional force between surfaces that are moving relative to each other
  • what sport would you want a low CoF and why?
    ice skating / skiing - to maximise speed and fluency over ice/snow
  • Which coefficient of friction (static or dynamic) is almost always higher?
    Static - This explains why it is harder to start moving a heavy sled than to keep it moving.
  • what does the term collision mean?
    when two or more objects come into contact with (exert forces on) each other during a short period of time.
  • What is Newton's 2nd law?
    Law of motion/acceleration - force is equal to mass multiplied by acceleration - the acceleration of an object is directly proportional to the net force acting