Motion T2

• Scalar Vs Vector Quantities

  A scalar quantity is a physical quantity that only has a magnitude.

  Eg: Mass, time

  A vector quantity has a magnitude and a direction.

  Eg: Weight, velocity
• Distance Vs Displacement

  Distance is how far something has moved. Scalar quantity.

  Displacement is the overall change of the position of an object. Vector quantity

  
• Speed Vs Velocity

  Speed:

  • scalar
  • the rate at which distance changes over time
  • Measure in m/s
  • = total distance/time

  velocity:

  • vector
  • the rate at which an object changes its position.
  • m/s
  • includes direction
  • = displacement/time
• v= s/t

  s= distance / displacement

  t= time

  v= average speed / velocity
• Average speed vs Instantaneous speed

  Average speed: The overall measurement of how fast something is moving

  Instantaneous speed: speed at any given instance in time
• What is acceleration?

  Acceleration occurs whenever the velocity of a body changes.

  Acceleration = change in speed or velocity / time taken
• a=v-u/t


  a = acceleration (ms^-2 or m/s/s)

  v = final velocity (m/s)

  u = initial velocity (m/s)

  t = time (s)
• Newton's First law of Motion?

  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 unbalanced force.
• Another Name for Newton's first law

  The law of inertia
• What is inertia?


  An object's tendency to resist changes in its motion.

  The amount of inertia which an object has depends in its mass. An object with a larger mass has greater inertia. This makes it harder to move.
• What is a force?


  A force is a push or pull that can cause an object to move, stop, or change direction.

  Needs to be written with a magnitude and a direction.
• What does Net force mean?

  The total amount of force acting on an object.

  Can be found by using free body diagrams
• Free body Diagrams


  Used to represent all the forces acting on an object:

  1. Use a square to represent the object
  2. Draw force with direction and magnitude
  3. Add vectors using vector addition
• Newton's second law


  An object will accelerate in the direction of an unbalanced force acting on it. The size of the acceleration depends on the mass and the size of the force

  Force = mass x acceleration
• What is inertial mass?

  The ratio of force to acceleration. Heavier masses have greater inertia meaning that it is harder to change their motion.

  Eg: If you push a bowling ball and a volleyball with the same net force the bowling ball will accelerate slower because it has greater inertia.
• Weight VS Mass

  Mass is a scalar quantity measured in kg that tells us how much matter is in an object.

  Weight is a measure of gravitational force in Newtons. Vector quantity.

  Fg=M x G

  Fg= weight force due to gravity

  m= mass kg

  g= acceleration due to gravity (9.8m^-2 on earth
• Newton's 3rd law of motion

  Every action has an equal and opposite reaction