NEWD linear motion

• scalar quantity are when measurements are only described in terms of magnitude
• vector quantity are when measurements are described in terms of magnitude and direction
• scalar quantities

  • mass - quantity of mass a body possesses
  • distance - path a body takes as it moves from a starting position to a finishing position
  • speed - body's movement per unit of time with no reference to direction
• vector quantities.

  • weight - gravitational force exerted on an object
  • displacement - shortest route in a straight line between the starting and finishing position
  • velocity - rate of change of displacement
  • acceleration - rate of change of velocity
  • momentum - product of the mass and velocity of an object
• an internal force is applied when out skeletal muscles contract
• an external force comes from outside the body
• weight/gravity

  gravitational force that earth exerts on the body, pulling it towards centre of earth, greater mass = greater force
• friction

  • static friction occurs before an object starts to slide
  • sliding friction occurs between two surfaces that are moving relative to one another
  • friction occurs in opposition to motion
  • it is affected by surface characteristics of both object, temperature of both surfaces and the mass of the objects
• air resistance.

  • opposes motion of body travelling through air
  • dependent on velocity of moving body, moving faster = greater resistance.
  • dependent on cross-sectional are of moving body, larger area means there is more air resistance.
  • dependent on shape and surface characteristics of moving body
• relationship between impulse momentum

  • impulse is the time it takes a force to be applied to an object or body
  • force x time
  • increase in impulse results in increase in change of momentum. this causes a larger change in velocity
  • to increase momentum through increasing impulse - more muscular force should be applied and the time over which the force is applied should be increased