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Pizza and level force

  1. Dec 20, 2015 #1
    1. The problem statement, all variables and given/known data
    A "peel" is a flat, long-handled shovel that a pizzaiolo uses to slide pizzas into and out of an oven. If a peel is 1.7m long and has a mass of 2.4kg and is carrying a pizza of mass 1.1kg as shown, what force must the pizzaiolo apply with his forward hand to hold the peel level?
    upload_2015-12-20_19-37-37.png

    2. Relevant equations
    Torque= rFsin0


    3. The attempt at a solution

    I tried solving this multiple ways, combining the mass 2.4kg + 1.1kg = 3.4kg or adding Fgrav =34.3kg sin theta= 0 since the force applied is up and the only other acting force is gravity which is down, however I also noticed that the position of the pivot (where we hold the shovel is to the right of the mass therefore the sin theta could also equal one and I tried with both of these equations and no success
     
  2. jcsd
  3. Dec 20, 2015 #2
    In your formula for Torque, θ is the angle between the lever arm -- the pivot to where the force is applied, and the downward force produced by gravity on the objects. Like you noticed, if θ=0, everything becomes zero and the math gives you nothing useful.
     
  4. Dec 20, 2015 #3
    Well I was completely wrong on this entire formula, so this is what I have found out.

    the correct area that this belongs to is dealing with the concept of simple machines. MA= li/lo and li Fi= lo Fo
    Fi= input force
    Fo= output force
    li= input lever
    lo= output lever

    ok so for this problem I did

    Fi= (3.5kg combined mass) (9.8g) 0.3(pivot)/1.7(length) =6.05N; then (3.5kg) (9.8g)-6.05N= 28.25N and MA=5.7 (li/lo) though something is wrong here but I'm not sure where I went wrong
     
  5. Dec 20, 2015 #4

    SteamKing

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    In order to hold the peel in equilibrium, the ∑F = 0 and the ∑M = 0 on the peel. The Pizzaiolo must apply forces with both hands to keep the peel from flipping, but the problem asks only what force he must apply with his forward hand. Think of this forward hand as the fulcrum and the peel as a lever. See if you can write some equations which describe this situation.
     
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