Fluid pressure physics homework

In summary: So … what's next?In summary, the mass of the liquid in the vat is approximately 1.04 x 10^4 kg. This was calculated using the equation PA=P_oA +mg where P is the pressure at the bottom of the vat, P_o is the atmospheric pressure, A is the area of the bottom of the vat, m is the mass of the liquid, and g is the acceleration due to gravity. Another method of calculation is using the pressure equation P- - P+ = rho gh, where rho is the density of the liquid and h is the depth of the liquid in the vat. Both equations give the same result.
  • #1
jason_r
27
0
A 0.800 m-diameter vat of liquid is 2.70 m deep. The pressure at the bottom of the vat is 1.20 atm.

What is the mass of the liquid in the vat?
 
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  • #2
Welcome to PF!

jason_r said:
A 0.800 m-diameter vat of liquid is 2.70 m deep. The pressure at the bottom of the vat is 1.20 atm.

What is the mass of the liquid in the vat?

Hi jason_r! Welcome to PF! :smile:

Show us what you've tried, and where you're stuck, and then we'll know how to help. :smile:

Hint: find the density first.
 
  • #3


tiny-tim said:
Hi jason_r! Welcome to PF! :smile:

Show us what you've tried, and where you're stuck, and then we'll know how to help. :smile:

Hint: find the density first.

so far i have :

PA=P_oA +mg
(1215600)(pi*(0.4)^2)= (1.013x10^5)(pi(0.4)^2) + 9.8m
m=1.04 x 10^4kg

I need confirmation on the answer and if I am doing this right
cause i don't have a key or anything
thanks
 
  • #4
jason_r said:
PA=P_oA +mg
(1215600)(pi*(0.4)^2)= (1.013x10^5)(pi(0.4)^2) + 9.8m
m=1.04 x 10^4kg

Yes, that's fine:

(I haven't checked your value for 1 atm … and I'm assuming you meant 10^6, so that it matches the 1215600)

You've used a force equation … force on the bottom minus force on the top = weight … P-A - P+A = mg.

You could also have use the pressure equation (that's the one I'd have used): P- - P+ = rho gh.

But they both give the same result, and they're both fine. :smile:
 

1. What is fluid pressure?

Fluid pressure is the force per unit area exerted by a fluid on its surroundings. It is caused by the collisions of molecules within the fluid and is dependent on the density, depth, and acceleration due to gravity of the fluid.

2. How is fluid pressure calculated?

Fluid pressure is calculated using the equation P = F/A, where P is pressure, F is force, and A is area. In fluid pressure, the force is the weight of the fluid above a certain point, and the area is the surface area of the object the fluid is acting on.

3. What is Pascal's principle?

Pascal's principle states that when an external pressure is applied to a confined fluid, the pressure is transmitted equally in all directions throughout the fluid. This allows for the use of hydraulic systems, where a small force can be multiplied into a larger force by using a confined fluid.

4. How does depth affect fluid pressure?

Depth has a direct effect on fluid pressure. The deeper an object is submerged in a fluid, the higher the fluid pressure will be at that point. This is due to the weight of the fluid above the object increasing with depth, causing an increase in pressure.

5. How does fluid pressure change with altitude?

Fluid pressure decreases with altitude due to a decrease in the weight of the fluid above a certain point. This is because as altitude increases, the amount of air above decreases, resulting in a decrease in the force exerted by the air molecules and therefore a decrease in pressure.

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