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Homework Help: Energy calculation

  1. May 28, 2009 #1
    Hi everyone!

    I am having a bit of a problem solving the following question (not good with maths), and would be very grateful for any advice given.

    1. The problem statement, all variables and given/known data

    A car is run for 400 hours per year, with a total mileage of 10,000 a year. The car uses diesel and consumes 2,000 litres per year. A litre of diesel cost £1.10 and holds 38.7MJ of primary energy.

    a) Calculate the mean engine power?

    b) If the engine is 20% efficient overall, how much energy would need to be stored in 95% efficient batteries to give a range of 300 miles on full battery charge?

    Many thanks,
  2. jcsd
  3. May 28, 2009 #2


    User Avatar
    Gold Member

    you say you're not good at math but that doesn't tell us where you need help at.

    Where is your attempt?
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