Biomechanics

• What is the definition of speed in measurement?

  Rate of change of position
• What is the definition of centre of mass?

  Point of balance of a body
• What factors affect stability in a body?

  Centre of mass and base of support
• What are the three classes of lever?

  1. First class lever
  2. Second class lever
  3. Third class lever
• Give an example of a first class lever in physical activity.

  Seesaw or triceps extension
• Give an example of a second class lever in physical activity.

  Wheelbarrow or calf raise
• Give an example of a third class lever in physical activity.

  Bicep curl or rowing
• What is the mechanical advantage of a first class lever?

  Varies depending on the position of the fulcrum
• What is the mechanical disadvantage of a third class lever?

  Always less than one
• What do Newton's laws of linear motion describe?

  • Relationship between body and forces
  • Body's motion in response to forces
  • Application to human movement
• What is linear motion?

  Motion in a straight or curved line
• How does a 100-metre athlete exhibit linear motion?

  Travels in a straight line during the race
• How does a 200-metre athlete exhibit linear motion?

  Travels in a curved line when running the bend
• What does Newton's first law of motion state?

  Every body continues in its state of rest or motion unless acted upon
• What is inertia?

  Resistance to change in state of motion
• How does mass affect inertia?

  Bigger mass means larger inertia
• Which rugby player would be easier to stop based on inertia?

  The winger weighing 75 kg
• What does Newton's second law of motion state?

  Force equals mass times acceleration
• How do you calculate force using Newton's second law?

  Force = mass × acceleration
• What is the force acting on Usain Bolt with a mass of 94 kg and acceleration of $9.5 \text{ m/s}^2$?


  $F =$$94 \text{ kg} \times 9.5 \text{ m/s}^2 =$$893 \text{ N}$
• What does Newton's third law of motion state?

  For every action, there is an equal and opposite reaction
• What is ground reaction force?

  Force exerted by the ground on a performer
• How does a swimmer demonstrate Newton's third law?

  Pushes back on water, water pushes forward
• How do Newton's laws apply to football?

  • Law of inertia: Ball remains still until kicked
  • Law of acceleration: Harder kick means faster ball
  • Law of action/reaction: Jumping player pushes ground, ground pushes back
• What is the formula for speed?

  Speed = Distance / Time
• How do you calculate speed in m/s?

  Speed = Distance covered / Time taken
• What is the speed of a sprinter running 100 metres in 12 seconds?

  $8.3 \text{ m/s}$
• How do you convert 30 minutes to hours for speed calculation?

  30 minutes equals 0.5 hours
• What is the speed of a student who runs 5.5 km in 30 minutes?

  $11 \text{ km/h}$
• What is a scalar quantity?

  Described in terms of size or magnitude
• What is the centre of mass?

  Point of concentration of mass
• How does the centre of mass change in the human body?

  Changes as the body moves
• Where is the centre of mass generally located in a standing position?

  Between the hip region
• How does gender affect the centre of mass?

  Differs according to gender
• What does the graph in Figure 5 show when a performer is stationary?

  The line on the graph is horizontal.
• What does a steeper line on a speed graph indicate?

  The performer is moving faster.
• Where is the centre of mass located in the human body?

  Between the hip region.
• How does raising your arms affect your centre of mass?

  It raises your centre of mass.
• How does the centre of mass differ between males and females?

  Males have a higher centre of mass.
• What factors affect stability in sports?

  • Height of the centre of mass
  • Position of the line of gravity
  • Area of the support base
  • Mass of the performer