### Discussion :: Hydraulics - Section 1 (Q.No.5)

Kanishk said: (Sep 10, 2013) | |

How come the answer is C? Initial Pressure in terms of ht. of water column= 1000/(1000*10)=0.1 m --- (i). Pressure @ 2.5 m depth in oil tank = 2.5*800*10. Representing above pressure as ht of water column, the answer comes out to be 2.0 m --- (ii). (i) + (ii) = 2.1m. |

Nikku said: (Oct 5, 2013) | |

Pressure head in terms of water = 2.5/0.8 = 3.1m. |

Hitesh Kumar said: (Dec 12, 2013) | |

Total pressure = ((.1*10^4)/1000)+(.8*2.5) = 3. |

Kumar said: (Nov 27, 2014) | |

Initial pressure is 1000 kg/m^2. Pressure at 2.5 m depth is 19620 kg/m^2. Total pressure at a depth 2.5 m is = 19620+1000 = 20620 kg/m^2. Depth in terms of water = 20620/(1000*9.81) = 2.1 m. |

Ruben said: (Mar 3, 2015) | |

From Basic Hydro static principle (FM text book by Frank m White). P = Pa-Gamma (Z2-Z1). Where Pa = Atmospheric pressure in n/m2 Z1 = 0 (Reference surface) and Z2 = negative downwards. = (0.98 n/m2-7848(-2.5)). = 19620.8 pa. H = (19620.8/(1000*9.81)) = 2 m of water. |

Nikita Patil said: (Mar 12, 2015) | |

How do you calculate the pressure at the given height? Please explain me. |

Manpraveen said: (Mar 25, 2015) | |

P = $gh. Pressure for oil = 0.8*1000*9.81*2.5 = 19620 n/m^2. Pressure for water = 1000*9.81*h = 19620. H1 = 19620/9810 = 2 m. H2 = atmospheric head = p/$g. H2 = 1000*9.81/1000*9.81= 1 m. Total head = H1+H2 = 2+1 = 3 m (Answer). |

Ma Murtaza said: (Jun 17, 2015) | |

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: (Jun 18, 2015) | |

1000/(1000+2.5*0.8) = 3. |

Rizgar Karim said: (Jul 27, 2015) | |

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. |

Ccjayesh said: (Feb 9, 2016) | |

Pa = 0.1 kg/cm2 = 1000 kg/m2. Poil = 800*2.5 = 2000 kg/m2. Total = 3000 kg/m2 = 3000/1000 = 3 meters of water. |

Anonymous said: (Jul 30, 2016) | |

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. |

Kailash Paliwal said: (Sep 18, 2016) | |

Atmosphere pressure =.1kg/cm2 = 1000 kg/m2. 1000kg/1000kg = 1m of water. Oil pressure = 2.5m = 2.5 *.8 = 2m of water. Total height = 1 + 2 = 3 m. Hence c is right. |

Bahram said: (Oct 4, 2016) | |

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. |

Komala Sai said: (Dec 22, 2016) | |

Patm = 0.1kg/cm^2 => 1000kg/m^2. Poil = (0.8 * 1000) * 2.5 = 2000 kg/m^2. Finally in terms of water = (1000 + 2000) ÷ 1000, = 3m of water. |

Rajani Patel said: (Feb 7, 2017) | |

Pressure at surface =10000kg/m^2. Pressure at a depth of 2.5 m=(2.5*9.81*800)=19620. Total pressure=29620. H=P/1000*9.81=29620/1000*9.81. H = 3.01m of water. |

Anonymous said: (Feb 20, 2017) | |

I think the answer should be 2 m. Because the atm pressure will be same for both oil surface and water surface. So it will be neglected. Please reply if anyone thinks I'm wrong. And do explain. Thanks. |

Jeevan said: (Feb 23, 2017) | |

Specific Gravity of oil is .8 & water is 1. So oil has less density the water therefor, water shows less head. So, the answer will be 2m not 3. |

Sashaus said: (Apr 6, 2017) | |

S1 h1 = s2 h2 or £1h1 = £2h2. £ = density , s= sp.gr. 1000 h1 = 800 * 2.5. H1 = 2 + 1 (initially pressure is 1) = 3. |

Er. Dipesh Yadav said: (Apr 15, 2017) | |

Atmospheric pressure = 0.1 * 9.81 * 100 * 100 = 9810 N/m2. Pressure at 2.5m depth = 0.8 * 9810 * 2.5 = 19620 N/m2. Total pressure at depth 2.5m = 9810 + 19620 = 29430 N/m2. Height in terms of water= 29430/9810 = 3m. |

Makar said: (Apr 28, 2017) | |

Yes, correct @Dipesh. |

Makar said: (Apr 28, 2017) | |

1 kg/m2 = 1000kg/cm2 this are correct. |

Suresh Yadav said: (May 26, 2017) | |

Yes, your answer is correct. Thank you @Dipesh. |

Gurmeet said: (Sep 25, 2017) | |

Simply P = density * gh. |

Waqar Ahmed Awan said: (Dec 28, 2017) | |

We know that; 1kg=9.81N and 1m=100cm. let atmosppheric pressure at top surface be; P1=denssity*g*h=0.1kg/cm2=0.1*9.81*100*100=9810N/m2. let pressure at heigt of 2.5m be p2=0.8*1000*9.81*2.5=19620N/M2. now total pressureP =p1+p2=9810+19620=29430N/m2. NOW pressure in terms of water =P/p1=29430/9810=3m so option C is correct. |

Prashant said: (Mar 24, 2018) | |

How (total pressure/atm pressure) is equal to the pressure head of water? Please explain anyone. Thanks. |

Nani Abdul said: (Aug 1, 2018) | |

Patm + (0.8)(2.5m)(9810N/m3) = Hh2o(9810N/m3). Patm = 0.1Kg/cm2 --> 1000Kg/m2. Patm = 1000Kg/m2(9.81m/s2) --> 9810N/m2 (Pa). 9810N/m2 + (0.8)(2.5m)(9810N/m3) = Hh2o(9810N/m3). Hh20 = (9810N/m2 + (0.8)(2.5m)(9810N/m3))/9810N/m3. Hh20 = 3mts. |

Amare Yihunie said: (Feb 2, 2019) | |

Specific gravity oil = 0.8. Density of oil=0.8*1000=800 kg/m3 Atmospheric pressure at surface of oil=0.1 kg/cm2=0.1*10000*10=20,000 pascal Pressure of oil at depth of 2.5 m = 800 * 2.5 * 10 = 10,000 pascal. Total pressure = 10,000 + 20,000 = 30000 pascal. In terms of water depth pressure = density of water * depth of water * gravity. The Depth of water = pressure/density * gravity = 30,000/(10000*10) = 3 meter. |

Govind said: (Feb 17, 2020) | |

The pressure at the bottom is 2.5x0.8x9.81= 19.62 KN/M3. Initial pressure at top= 0.1 kg/cm2= 0.1x98.06=9.80 KN/M3. Total pressure at Bottom =19.62+9.80 =29.42 KN/M3. Head= 29.4/9.81 =2.99 =3.00 Metre. |

Saurabh Kaday said: (Mar 5, 2020) | |

Don't understand clearly. Anyone, please solve it by standard formula with step by step with meaning. |

Ravinder said: (Apr 11, 2020) | |

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. |

Pawan Pandey said: (Apr 22, 2020) | |

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. |

Pavan said: (May 3, 2020) | |

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? |

Vikas said: (Nov 11, 2020) | |

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. |

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