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Am i correct in getting a low value?

  1. Nov 7, 2006 #1
    A crane uses its petrol engine to lift a beam of mass 103 kg by height
    h. The fuel burned loses 1 MJ (106 J) of chemical potential energy, 85%
    of this being transferred by heating to the air. The internal energy of the
    crane’s engine increases by 4.0×104 J, while that of the crane’s superstructure
    and the beam is unchanged. The crane’s superstructure (not engine or fuel)
    increases in gravitational potential energy by 104 J. Everything is at rest
    before and after. Assume all transfer by working out of the crane is used to
    lift the beam.
    (a) [10 marks] The calorific value of the fuel is 43 MJ kg−1, its density is 737
    kg m−3 and it costs 90p per litre (there are 1000 litres in 1 m3). What was
    the fuel cost of raising the beam?
  2. jcsd
  3. Nov 7, 2006 #2
    I tried to apply lots of the basic energy conservations laws but get stuck when approaching an answer making me very depressed. Sympathy work well on here?
  4. Nov 7, 2006 #3
    Lets see your working so far and where you are are stuck.
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