Forces and Electricity

• A force can change an object's:

  • Speed
  • Shape
  • Direction
• A force can be a push and pull.
• Forces are measured in Newtons (N).
• A newton balance can be used to measure forces.
• Newton Balance:

  • The balance is held at the top.
  • The object is attached to the hook.
  • The reading is read off the scale.
• Friction is a force that opposes motion.
• Ways to increase friction:

  • Making the surfaces rough.
  • By pressing the surfaces harder against each other (by increasing normal force).
  • By removing the lubrication between the surfaces.
  • By using sliding motion rather than rolling motion.
  • By increasing the surfaces area in contact.
• Ways to decrease friction:

  • Lubrication.
  • Streamlining.
  • Ball bearing.
  • Make surfaces smooth by grinding.
  • Reduce pressure on the object.
  • Use rolling friction instead of sliding friction.
  • Reduce contact between surfaces by electrostatic magnetic levitation.
• Lubrication


  Is adding some oil of grease to reduce friction.
• Streamlining


  Is changing the shape of objects so the drag is reduced, and they can travel faster through air or water.
• Ball Bearing


  Is to reduce friction in wheels or cogs, you can add ball bearings. these small balls mean the ring will roll rather then "rub", so there will be less friction.
• Weight is a force due to gravity pulling an object downwards. It is measured in Newtons.
• Mass is the amount of matter in an object, measured in kilograms.
• Gravity lets us know know how much force is exerted on a 1 kg mass.
• W = mg 


  Weight = mass x gravity
• A complete circuit has a path going from one side of the battery to the other. There are no gaps and all components are working.
• Current is the number of charges passing a point every second. It is measured in amperes (A).
• An ammeter is connected in series and measures current.
• Voltage is the energy given to each other coulomb of charge. It is measured in volts (V).
• A voltmeter is connected in parallel and measures voltage.
• In a series circuit, all of the components are in one big loop.
• The current in a series circuit is the same everywhere.
• The voltage across the components adds up to the supply voltage.
• In a parallel circuit, the components are arranged in branches.
• The voltage in a parallel circuit is equal to the supply voltage.
• Inside an electrochemical cell is a mixture of chemicals.
• When a chemical reaction takes place, energy can be released.
• The chemicals in cell react to produce electrical energy
• All that is needed to make an electrical cell is:

  • Two different metals connected in a circuit with wires.
  • The circuit between the metals completed with a solution that conducts electricity.
• Zinc and copper are often used in electrochemical cells.
• Lemon juice is a good conductor as it contains ab acid called citric acid.
• Chemical cells are more commonly referred to as batteries. They usually contain chemicals that react together to make electricity.
• A chemical cell is made of:

  • 2 different metals (electrodes).
  • A conducting solution (electrolyte) that completes the circuit to let electrons flow.
• In a battery the electricity comes from a chemical reaction inside the metal casing.
• The electrons move from the negative end of the terminal.
• A simple cell can be created by connecting two different metals in contact with a conducting solution.
• The voltage in a cell can be effected by changing variables such as the metals or the solution.
• Friction causes "energy loss" as it slows down movement. Reducing the friction will reduce the energy lost and improve the efficiently (e.g. how the machine works).