Physics unit 1

• Circular/Cylindrical


  • Thickness, length, mass, etc.
• Diameter


  Measure for a large number
• Circumference


  Divide by 6
• Density


  Measure time for 20 complete oscillations, then divide by mass for unit volume
• Volumes


  Length x Width x Height (except mercury)
• Liquids and Solids
• Area of base x height
• Kinematics


  Distance/time, Speed/time
• Kinematics


  • Slope = speed, Distance = area under graph
• Constant speed


  Positive slope
• Acceleration

  Positive slope
• Deceleration

  Negative slope
• Not moving

  Slope = zero
• Average speed

  Total distance / total time = area under graph
• Free fall acceleration = 9.8m/s^2
• A body remains at rest or in constant speed unless acted upon by an external force
• For the same object, weight can change from place to place but mass is always constant
• Friction in fluids

  • Depends on shape, size, speed, and density of the fluid
• Extension


  Extended length - original length
• At rest or moving with constant speed

  No acceleration
• Accelerating or decelerating

  Acceleration
• Moment


  Force x Distance (from pivot)
• Clockwise moment = anti-clockwise moment
• For an object to be in equilibrium: 1) Resultant forces = 0, 2) Resultant moment = 0
• Weight


  W = mg
• Pressure in liquids


  Affected by depth and density only
• Drag and friction
• Newton's 1st law
• Advantages and disadvantages of inertia
• Newton's 2nd law


  F = ma
• Pressure at same depth is the same
• Pressure can change with size/shape/speed/direction
• Combining forces


  Resultant force = 0, Resultant moment = 0
• Work done = Force x Distance (moved in direction of force)
• Power


  Work done (or energy) / time
• Energy stores


  • Moving object
  • Raised object against gravity
  • Hot to cold
  • Nucleus of atoms
  • Chemical bonds between atoms
  • Chemical reactions
  • Wind driving generators
  • Solar to heat
  • Solar to electric
  • Chemical in living organisms
• Fossil fuels formed from decayed organisms, burned to release thermal energy
• Advantages and disadvantages of renewable energy sources
• Nuclear fusion


  2 Helium nuclei fuse to form 1 Hydrogen nucleus, releasing energy
• Nuclear fission


  Heavy nucleus bombarded with neutron, splitting into smaller nuclei and releasing thermal energy