Calculate mass of tank floating in freshwater

  • Thread starter Parsifal1
  • Start date
  • #1
61
3

Homework Statement


A rectangular tank contains 6L of freshwater, has a floor area of 0.3m^2 and floats upright in freshwater. If the bottom of the tank is 150mm below the surface of the water, calculate the mass of the tank.

Homework Equations


F=P*A=pgAh

The Attempt at a Solution


1000*9.81*0.3*0.15=441.54N 441.45/9.81=45kg
 

Answers and Replies

  • #2
billy_joule
Science Advisor
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A rectangular tank contains 6L of freshwater... calculate the mass of the tank.
I think you're expected to find the mass of just the tank( excluding the water).
 
  • #3
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I think you're expected to find the mass of just the tank( excluding the water).
That's what I don't understand, 6L=6Kg, should it be mass=0.03*1000=mass*density?
 
  • #4
billy_joule
Science Advisor
1,200
331
You've found the mass of the tank and water in post #1; 45kg.
If there's 6kg of water in the tank, how much does just the tank weigh?
 
  • #5
61
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You've found the mass of the tank and water in post #1; 45kg.
If there's 6kg of water in the tank, how much does just the tank weigh?
-15Kg? How can the mass of the tank and the water weigh less than the water? Am I using the right formula for the mass of the tank+water?
 
  • #6
61
3
Should I do 0.3*0.15*1000=P=pyh=45 Then take 45 from 60? I get the wrong answer by doing that? :/
 
  • #7
61
3
If the weight of the water displace=buoyant force, then is the mass of the tank the buoyant force over 9.81? As the mass of the object is equal to the mass of water displaced.
 
  • #8
61
3
I found the answer:

density=mass/volume
mass=density*volume
1000*(0.3*0.15)=45
45-6=39Kg

Thanks for the help.
 

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