fluid mechanics

10 Answers

106
Asish Mahapatra ·

Leave the first two questions..

Q3. What is the pressure at a point just below the bottom surface ot the block?

Q4. What is the pressure at the bottom most point of the fluid system ?

3
iitimcomin ·

3/2rogH + 1/4(3/4)(1/5)rogL - 3/4(1/4)(1/5)(rogL) [Q4]

3
iitimcomin ·

1/2rogH + 1/4(3/4)(1/5)rogL - 3/4(1/4)(1/5)(rogL) + (1/4)2roLg [Q3]

24
eureka123 ·

Ans3
Patm+ρgH/2+2ρg(L')

L'=0.25L

Ans4 Patm+ρgH/2+2ρgH/2

106
Asish Mahapatra ·

Ans 4. was Patm + ρgH/2+2ρgH/2 + M(body)g/A(body)

Why this extra term??

Ive seen this answer in atleast two books.. (arihant and GC Agarwal)

Ans 3. Seems fine

24
eureka123 ·

well in that case that term should be in ans3 tooo

106
Asish Mahapatra ·

Another similar question.

Consider a system in which liquid of density d is there upto a height h and base area of container A. A small object of mass M and base area a is floating in the container. What is the pressure at the bottom of the fluid system?

106
Asish Mahapatra ·

Really its got me confused...

for Q3. its explanation was that acc, to law of floatation, P=P0 + dgh/2 + 2dgh/2 because this balances the weight of the body.

for Q4. It found total weight on bottom surface divided by area.

Which method is correct??

Finding total weight and dividing by base area

or finding pressure

that was my first question..

For calculating pressure can we replace the block by respective fluids (according to the volumes immersed in either) and dfind out the pressure at the bottom?

1357
Manish Shankar ·

For question 3
answer is P=Patm+ρg(H/2)+2ρg(L/4)

For question 4
answer is P=Patm+ρg(H/2)+2ρg(H/2)

The question for the given answer(given by asish) is
Suppose you have liquids of density of ρ and 2ρ and height H/2 and H/2. Now drop a block of lenght L and density 5ρ/4. Then the answer given by asish is correct.

106
Asish Mahapatra ·

Thank you sir,

The confusion arose because it was prev iit ques in which it had asked to find out density of block (the lengths were given) which i calc to be 5d/4. For the pressure at bottom most point Arihant (31yrs) had given ans what i have written so had GC aggarwal and Aakash.

Teen teen sources se ek hi answer se main confuse ho gayaa..

Anyways thanks to u and eureka

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