Conservation of Energy and Power | Improve Tuition | Tutors | Tuition | Tutoring | Tutor

Conservation of Energy and Power


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  • Energy is NEVER CREATED OR DESTORYED
  • Conservation of energy principle: energy can be transferred usefully, stored or dissipated (spread out) but can never be created or destroyed.
  • When energy is transferred between stores, not all of the energy+ is transferredusefully to the store you want it to go to. Some energy dissipated = wasted energy = not being stored in a useful way (usually thermal energy stores)
  • Mobile phone: energy transferred from the chemical energy store in battery (useful). Some energy is dissipated as thermal energy (wasted )
  • Power = rate of energy transfer OR rate of doing work. It is measured in watts
  • 1 watt = 1 joule of energy transferred per second
  • P= e/t
  • Power (w) = energy transferred (j) / time (s)
  • P=W/t
  • Power (w) = work done (j) / time (s)
  • Power (w) = work done (j) / time (s)
  • Powerful machine = transfers lots of energy in a short amount of time
  • Two cars which are identical except they both have different engine powers. Both cars race the same distance to a finish line. The car with the more powerful engine will reach the finish line faster than the other car.
  • 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.

     

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    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.

     

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    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.

     

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

    1.

    2.

    3.

    4.

     

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