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