Chair leg pressure problem geez

  • Thread starter caseys
  • Start date
  • #1
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Chair leg pressure problem....geez

Homework Statement



A 63kg person sitting on 3.5kg chair. Four legs contact the floor, each leg with circle 1.2cm in diameter. Find pressure exerted on floor by each leg of chair (weight evenly distributed).


Homework Equations



[{(person mass) + (chair mass)} * (9.81)] / pi (radius contact circle in meters)(4 chair legs)

The Attempt at a Solution



63kg + 3.5kg = 66.5kg total

1.2cm diameter = 0.6cm radius = 0.006m radius

area = 0.00011304 m^2 each leg
area total four chair legs = 0.00045216 m^2

P = F/A

{(66.5)(9.81)} / 0.00045216 = 1442774.68 N/m^2

...thus for one leg = 360693.67 N/m^2

answer of 3.6E5 and 3.61E5 incorrect.

Answer unit requested is Pa.

What am I missing here?
 

Answers and Replies

  • #2
Fermat
Homework Helper
872
1
The pressure is the same for all four legs. You shouldn't have divided by 4.

Pressure (on each/all chair leg(s)) = (total force) / (total area) = (partial force) / (partial area)
 
  • #3
14
0
Goofy err on my part. Actually had the answer correct the first time with 1442774.68 but posted my answer as 1.4E6....the correct way to post my answer was 1.44E6

Thank you
 
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