Conduction and Convection



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  • Conduction = process where vibrating particles transfer energy to neighboring particles . Mainly happens in solids
  • if an object is heated the energy is transferred to the thermal energy store of the object= energy shared across the kinetic energy stores of the particles in the object
  • particles which are being heated vibrate more and collide with each other = collisions cause energy to be transferred between particles’ kinetic energy stores = conduction
  • This continues throughout the object until the energy is transferred to the other side of the object.
  • Thermal conductivity = measure of howquickly energy is transferred through a material in this way. High thermal conductivities = transfer energy between particles quickly.
  • Convection = energetic particles move away from regions
  • Happens in liquids and gases as particles are free to move around. Heat a gas or liquid = particles move faster = space between particles increases = less dense region
  • Liquids and gases can flow = warmer and less dense regions will rise above denser and cooler objects.Constant heat source = convection current
  • Radiator creates a convection current
  • 1. Energy transferred from the radiator to nearby air particles = conduction
    2. Air by radiator = warmer = less dense
    3. Warm air rises = replaced by cooler air = cooler air heated by radiator
    4. At same time = previously heated air transfers energy to surroundings = cools = more dense = sinks
    5. Cycle repeats = flow of air circulates the room = convection currents.

    How long have you…? (present perfect 4) Exercises


     

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    Use the information given to create questions beginning with ‘How long…?’

    • It is snowing.

    • The weather is shining.

    • John and Kate are married.

    • My brother has gone on holiday.

    • My aunty and uncle live in Canada.

    • My sister is a teacher.

    • I work at the chemist.

    • I’ve known Susan since I was a baby.

    • Jonathan is learning to speak to Mandarin.

     

     

     

    Fill in the missing gaps in the sentences using the present perfect (=has/have + past participle)

    • I have known Kate a long time.

    • My brother has been playing the piano he was 11 years old.

    • My mum and dad on holiday to America. They

    gone since last Sunday.

    • I Ben and Emma since primary school.

    We to the same primary and secondary school.

    • My sister learning to speak French because she
    is going to France next month.

     

     

    Use the appropriate words in the missing gaps.

    have you lived       lives      to

    has been       works        have known

    I have bought       have worked.

    • My sister in Spain. She is studying Spanish

    with her friend Rosie. I Rosie since I was 5.

    • Spencer like with Jamie. They have worked

    together for 2 years.

    • How long in Australia?

    • a new dress for prom.

    • He to Thorpe park.

     

     

    Challenge: Create 4 of your own questions beginning with ‘How long……?’

    1.

    2.

    3.

    4.

     

     

     

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