forces

• what are scalar quantities?

  only have magnitude
• what are vector quantities?

  have a magnitude and a direction
• what are 5 examples of scalar quantities?

  • speed
  • distance
  • mass
  • time
  • temperature
• what are 5 examples of vector quantities?

  • force
  • displacement
  • momentum
  • velocity
  • acceleration
• what are forces?

  a push or pull on an object caused by it interacting with something
• what are 4 examples of contact forces?

  • friction
  • tension
  • air resistance
  • normal contact force
• what are 3 examples of non contact forces?

  • electrostatic force
  • gravitational force
  • magnetic force
• what is weight?

  force that acts on an object due to gravity
• what is weight measured with?

  calibrated spring balance
• what is the centre of mass?

  point at which an objects weight appears to act
• what is the difference between mass and weight?

  • mass = same anywhere in universe
  • weight = depends on strength of gravitational field at object location
• what are 2 types of deformation?

  • elastic = object goes back to original shape and length after forces have been removed
  • inelastic = object doesn't go back to original shape and length after forces have been removed
• what is a moment?

  turning effect of a force
• what are gears?

  used to transmit the rotational effect of a force from one place to another
• what are levers?

  make it easier to do work
• how do levers work?

  1. increasing distance between pivot and applied force
  2. less force required to get same moment
  3. easier to lift load
• what does the pressure of a fluid mean?

  a force is exerted normal to any surface in contact with fluid
• what happens to the pressure if a liquid is denser?

  pressure increases
• what is upthrust?

  resultant force acting upwards on an object submerged in liquid, due to pressure of liquid being greater at bottom of object than at top
• what happens to the upthrust if the object is denser than liquid?

  less so object sinks
• what is the atmosphere?

  a thin layer of air that surrounds earth
• where is atmospheric pressure created?

  on a surface by air molecules colliding with surface
• how does atmospheric pressure decrease?

  1. height above earth increases
  2. number of air molecules and so weight of air, above a surface, decreases
  3. atmospheric pressure decreases
• what is distance?

  how far an object has moved
• what is displacement?

  distance and direction in a straight line from an objects starting point to its finishing point
• what is speed?

  how fast you're going with no regard to direction
• what can peoples walking / running/ cycling speed be affected by?

  • type of ground
  • ability
  • age
  • distance travelled
• what is the average speed of a person walking, running, cycling?

  • walking = 1.5 m/s
  • running = 3 m/s
  • cycling = 6 m/s
• what is the average speed of a car, train, plane, sound?

  • car = 25 m/s
  • train = 30 m/s
  • plane = 250 m/s
  • sound = 330 m/s
• what is velocity?

  speed in a certain direction
• how does an object have a changing velocity?

  object in circular motion with constant speed is always changing direction, so object has changing velocity
• what is acceleration?

  change in velocity in a certain amount of time
• what is deceleration?

  negative acceleration