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Human efficiency (Physics calculations)

Discussion in 'General Discussion' started by FreeStream, 13 May 2006.

  1. FreeStream

    Capodecina

    Joined: 10 Apr 2004

    Posts: 13,320

    Now, a team of around 4 people have lifted 4298 kg 4.5 meters into a cargo hold.

    Joules = weight x distance moved

    4298x10=42980 Newtons
    42980x4.5=193410 Joules or 193.41kJ.

    Over 4 people thats 48.3525kJ each. This is all rough :p

    Now, a slice of bread is ruffly 500kJ, so we cant have used 10% of a slice of bread each to lift 1 ton each.

    Even if we are 10% efficient, thats still a slice of bread to life 1 ton. Unless we are less than 1% efficient, that doesn't seem right to me :confused:

    So, what am I doing wrong :o
     
  2. Ricochet J

    Capodecina

    Joined: 29 Jun 2004

    Posts: 12,890

    Yes but you have to realise Energy comes from other places in our body too, if my memory serves me correctly, through both aerobic and anerobic respiration :)
     
  3. FreeStream

    Capodecina

    Joined: 10 Apr 2004

    Posts: 13,320

    But surely the food energy (chemical) is used abit to respire?

    No food = no energy = dead?
     
  4. Ricochet J

    Capodecina

    Joined: 29 Jun 2004

    Posts: 12,890


    Glucose + Oxygen = Carbon Dioxide + Water + Energy

    Glucose comes from many sources, not just food. And off course oxygen is oxygen. The products are Co2, H20 and Kj

    Edit: Even if the food was supplying the Glucose the body would use Glucose reserves in the Gall Bladder (I think it's stored there) for anerobic respiration.

    Edit 2: For anerobic respiration, Glucose ---> Lactic Acid + Energy. The lactic acid builds up in the muscles when using reserves, that is why your muscles feel like rubber and feel a burning sensation when doing something active like sport or going to the gym :)
     
    Last edited: 13 May 2006
  5. FreeStream

    Capodecina

    Joined: 10 Apr 2004

    Posts: 13,320

    Yeee :), I pretty much knew all that BUT the glucose first came from a food source. So now its in the body, what is the efficiency? :confused:

    Eg. Eat, then start lifting/running/exercise, what % of that energy in the food is used to lift/propell you? :confused: :o

    CR.
     
  6. Ricochet J

    Capodecina

    Joined: 29 Jun 2004

    Posts: 12,890

    We need a Biologist. All this stuff that's coming out of my mouth is my GCSE biology days.
    I am now an A Level Physicist! :D
     
  7. FreeStream

    Capodecina

    Joined: 10 Apr 2004

    Posts: 13,320

    :D

    Im coming to the end of my GCSEs, going on to A level Physics (got A* in mocks in Physics lol - Maths and geography :D :cool:
     
  8. Ricochet J

    Capodecina

    Joined: 29 Jun 2004

    Posts: 12,890

    Good stuff :)