Year 8 Physics

lesson: 1 objectives: 1-5

• forces are measured in newtons using a spring balance
• there are two main force categories:
  • contact
  • friction, buoyancy, tension, applied forces
  • non-contact
  • normal forces, gravitation, magnetism, electrostatic forces
• force definitions:
  • frictional force - the force exerted by a surface as an object moves across it or makes an effort to do so
  • air resistance - a special type of frictional force that acts upon objects as they travel through the air
  • tension force - force that is transmitted through a string, rope, cable or wire when it is pulled tight by forces acting on opposite ends
  • spring force - the force exerted by a compressed or stretched string upon any object attached to it

lesson: 2 objectives: 6-8

• balanced force - in constant speed or not moving
• unbalanced - speeding up or slowing down

lesson: 3 objective: 9

• gravity is increased by mass or distance
• weight - a force and changes depending on gravity - mass multiplied by gravitational force
• mass - amount of matter, stable
• types of friction - static (between 2 non moving items), sliding (object moving over another, rolling (e.g. ball)
• newtons first law - remains in motion unless acted upon by an unbalanced force

lesson: 4 objective: 12-13

• many different types of energy - heat, sound, mechanical, nuclear, chemical etc.
• energy can be hard to define, but it is:
  • the ability to do work
  • work occurs when changes occur to matter
  • work = force x distance
  • W = F x s
• energy is measured in the same unit as work: joules

lesson: 5 objective: 13

• 2 main types of energy : kinetic and potential
  • kinetic - moving
  • potential - a store of energy ; can happen but hasn’t happened yet
• heat / thermal - the interhal motino of the atoms is called heat energy
  • can be produced by friction
  • causes changes in any form of matter
• chemical energy - energy that is available for release from chemical reactions
  • chemical is energy to required to bond atoms together, but when the bonds are broken, energy is released
  • example: fuel or food
• electromagnetic energy - waves of energy
  • light, x-rays, lasers, commonly used in power lines
• nuclear energy
  • radioactive atoms have an unstable nucleus which causes it to split
  • when the nucleus splits it releases energy
• sound energy
  • anything that makes a noise has this form of energy
• mechanical energy - anything that moves

lesson: 6 objective: 15

• energy transfer - energy is transferred from one object to another
  • examples:
  • frying an egg
  • kicking a soccer ball
  • opening a door
  • dropping something
  • throwing something
• energy transformation - energy is transformed from one energy type to another
  • burning something !!
  • lighting a light bulb
  • driving a car

lesson: 7 objective: 15-17

• temperature - the amount of heat energy available for work in a system
  • this relates to the average kinetic energy
• higher temperatures means higher moving particles
• heat flows from hot to cold
  • thermal equilibrium - the same temperature
• all phases of matter expand with higher temperature
• heat transfer is a transfer of kinetic energy - heat is energy in transit, and measured in joules
  • heat will always flow from hot to cold until thermal equilibrium
  • heat is transferred via three processes - conduction, convection and radiation
• conduction - particles that are very close together can transfer heat energy as they vibrate. this type of heat transfer is called conduction
• solids are good at conducting heat while liquids and gases are worse