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posted by  moreliano767 on 11/10/2007 11:22:30 AM  |  status: Live  

when would pressure double at the surface

Course Textbook Chapter Problem
Algebra Based Physics N/A N/A N/A
Question Details:
How deep under the surface of a lake would the pressure be double that at the surface ? ( 1 atm = 1.01x 105 Pa)
POSSIBLE ANSWERS:
a. 1.00m
b. 9.80m
c. 10.3m
d. 32.2m
e. 42.6m
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Oracle
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(Ecole Polytechnique Fédérale de Lausanne)
posted by Golden Monkey on 11/10/2007 11:27:17 AM  |  status: Live
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moreliano767's comment:
"thanks"
Response Details:
You want to find the depth of water at which the pressure of the water is 1 atmosphere, because at the surface the pressure is 1 atm, so at depth it would be 2 atm (one from the air, one from the water)
 
The pressure of the water is     p  = ρ g d         where d is the depth  so
 
     101000  =  1000 * 9.8 * d
 
   d   =   10.3  meters
Mentor
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(Houghton College)
posted by ktqu on 11/10/2007 11:30:40 AM  |  status: Live
Asker's Rating: Helpful   
moreliano767's comment:
"thank you i appreciate your help"
Response Details:
Use the equation P = P0 + ρgh
 
P0 = the pressure at the surface (1.01 * 105 Pa)
P = pressure at depth (2 * 1.01* 105)
ρ = density (for water, ρ = 1000 kg/m3)
g = gravity (9.8 m/s2)
h = depth
 
202000 Pa = 101000 Pa + (1000kg/m3)(9.8 m/s2)h
h = 10.3 m
 
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