Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Pressure exerted by 1 leg of a chair.

  1. Apr 15, 2012 #1
    1. The problem statement, all variables and given/known data
    Estimate the pressure exerted on a floor by one pointed chair leg (64kg on all four legs) of area = 3.0×10−2 cm^2.

    3. The attempt at a solution
    first i found the weight of the chair (mg) to be 627.2 N, and the weight on 1 leg is 1/4th of that, so the weight on one leg is 156.8 N. then i convert .03x10^-2 cm^2 to m^2 by dividing by 10000 to get 3x10^-6. Since pressure is =F/A , i take 156.8/3x10^-6 to get 5.2x10^7 or 52,266,666 which i have a hard time believing is correct.
     
  2. jcsd
  3. Apr 15, 2012 #2

    OldEngr63

    User Avatar
    Gold Member

    Go back over your arithmetic. I think you have an error in what you have laid out here.
     
  4. Apr 15, 2012 #3
    well i did see that i typed the given area of the bottom of the chair leg wrong while i was describing what i did thus far, but aside from that the conversion from cm^2 to m^2 seems correct to me (3x10^-2 → 3x10^-6). unless my method for coverting was done incorrectly.
     
  5. Apr 15, 2012 #4

    gneill

    User Avatar

    Staff: Mentor

    Your result looks okay; After all, these are rather sharp chair legs! With a cross sectional area of 3 x 10-2 cm2, if they're circular then their radius is about 1 mm. The hardwood floors would sure take a beating!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook