Civil Engineering - Hydraulics - Discussion

Discussion Forum : Hydraulics - Section 1 (Q.No. 5)
5.
If the atmospheric pressure on the surface of an oil tank (sp. gr. 0.8) is 0.1 kg/cm2, the pressure at a depth of 2.5 m, is
1 metre of water
2 metres of water
3 metres of water
3.5 metres of water
4.0 metres of water.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
42 comments Page 3 of 5.

MA MURTAZA said:   1 decade ago
p*ATM = 0.1 kg/cm*2 = 1000 kg/m*2 = 9810 N/m*2.

p*oil = 19620 N/m*2 (after calculation).

Total pressure = 29430 N/m*2.

Hence, h*water = 29430/9810 = 3 m of water.

Abdilahi khalif said:   1 decade ago
1000/(1000+2.5*0.8) = 3.

Vikas said:   5 years ago
If we will consider the value of g then the pressure will come in the unit of Newton/square meter.

For determining the value of pressure in the form of kg/m2 we can't use Value of g.

Pavan said:   5 years ago
How the pressure at 250 cm comes out as 2000 Kg/m2?

That will be $gh, we don't consider 'g' value.

Can anyone explain me?

Pawan pandey said:   5 years ago
0.1*10^4 kg/m2= 1000 kg/m2.
0.8*1000*2.5= 2000 kg/m2,
1000+2000= 3000 kg/m2 ( pressure ),
3000/1000= 3 m of water.

Ravinder said:   5 years ago
Patm=0.1kg/cm^2=10,000Kg/m^2.
Pressure at 2.5m=0.8*1000*0.8*2.5=19620Kg/m^2.
Total pressure at 2.5m=10,000+19620=29620Kg/m^2.
But in option, we need pressure in terms of head=Pressure/(Density*g)
H=29620/(9.81*1000)=3.1~3m of water column.

Saurabh kaday said:   5 years ago
Don't understand clearly.

Anyone, please solve it by standard formula with step by step with meaning.

Rizgar Karim said:   1 decade ago
Patm = 0.1kg/cm2 = 0.1*10000*9.81/1000 = 9.81 KN/m2.

Poil = 0.8*9.81*2.5 = 19.62 KN/m2.

Ptotal = Patm + Poil.

Ptotal = 19.62 + 9.81 = 29.43 KN/m2.

P in-term of water = 29.43/9.81 = 3m of water.

Bahram said:   9 years ago
First Patm = 0.1kg/sq/cm = 1000 kg/sq.m.
Now Poil = S(oil) * ρ(water) *h(oil) => 0.8 * 1000 * 2.5 = 2,000 kg/sq.m.

So, P(total at bottom) = 2,000 + 1,000 = 3,000 kg/sq.m.

Now h(pressure in terms of head of water) = P(total)/ρ(water) => 3,000 kg/sq.m/1,000 kg/cu.m = 3 m of water.

Anonymous said:   9 years ago
P2 = P1 + Density(H); P1 = 0.1kg/cm^2 or 1000kg/m2.

Density of oil = specific Gravity x 1000 kg/m3.
= 800kg/m3 (Note: 1000kg/m3 is the density of water).
P2 = 1000 + 800 x 2.5 = 3000kg/m2.
Pressure in H of Water = 3000/1000 = 3.0m.


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