The Physics of Sports

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The Physics of Sports

• By Liaisha White

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Football

• Momentum plays a large part in football
• Momentum is conserved throughout collisions with
  other players
• It takes a force, change in direction or change
  in velocity to change momentum
• In tackles, inelastic and elastic collisions
  occur
• Inelastic collision occurs when the two bodies
  are stuck together forming one mass after the
  collision, during these collisions kinetic energy
  is reduced
• Elastic collisions occur when two objects collide
  and then separate, during these collisions
  kinetic energy is conserved
• Newtons third law states that for every action
  there is an equal and opposite reaction, so the
  player tackling his opponent must also be able to
  sustain the force he is exerting
• One can calculate the force with which a player
  is hit by using Newtons second law

PMV FMA
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Golf
vf vi at d vit 1/2at2 Vf2 vi2 2ad

• A golfers swing is an example of torque (using a
  force to create rotation)
• The golfer twists their hips and shoulders to
  swing the club
• This energy that is exerted is transferred to the
  club head, which propels the golf ball when the
  two collide
• Projectile motion also plays a large part in the
  flight of the golf ball
• There are certain ideal angles to hit the ball in
  order to either maximize or minimize the distance
  it which it travels
• 45 degrees is the optimal angle for maximum
  height
• In absence of air resistance projectiles launched
  at complimentary angles have the same range
• There are also several equations that when used
  one can calculate the distance traveled by the
  golf ball

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Skiing

• Potential and kinetic energy play a large role in
  this sport
• While on the ski lift or on the hike up you gain
  potential energy
• When gravity pulls you down the hill it is turned
  into kinetic energy
• The farther one travels the harder they work
  against gravity and the more potential energy
  they gain
• All this potential energy is then transformed
  into kinetic energy when one begins to travel
  down the hill
• In the end the law of conservation of energy
  holds true (Energy cannot be created or
  destroyed it may be transformed from one form
  into another, but the total amount of energy is
  never changed)
• The amount of potential energy one gained is
  equal to the amount of kinetic energy they used

PEmgh KE1/2mv2 PEKE
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Ice Skating

• Angular momentum is large part of spinning in
  figure skating
• In order to perform a spin or jump with several
  rotations in the air, the skater must generate
  angular momentum
• Angular momentum is generated by applying a force
  against the ice, the ice then applies a ground
  reaction force on the skater, giving them angular
  momentum
• The larger the force or farther the force is from
  the axis of rotation, the larger the torque, the
  larger the torque, the larger the angular
  momentum
• If the ice skater lengthens the moment of inertia
  they will increase their angular momentum
• If a figure skater wants to generate a lot of
  angular momentum they should have their arms
  spread wide, increasing their moment of inertia,
  in this position they will have to have a large
  torque to stop rotating and their angular
  momentum will be larger than if they started
  spinning with their arms at their sides

Angular Momentum mvr Torque rFperp Rotational
Inertia m1r12m2r22
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Bibliography

• http//www.physics.ox.ac.uk/schools/inset/Ski-phys
  1.htm
• Hewitt,Paul G. Conceptual Physics Tenth Edition.
  St. Petersburg Pearson Addison Wesley,2006.
• http//footballphysics.utk.edu/run.htm
• http//btc.montana.edu/olympics/physbio/biomechani
  cs/cam02.html
• http//sportsillustrated.cnn.com/augusta/cool_stuf
  f/physics/