Is anyone good with pressure/density related mcqs in AS Physics?? I need to get 3 mcqs answered?

[Peter Check]

These are the 3 question I cannot do, can anyone help me out??

 

[fathimaash]

k i think i can help u with da last question Q21
da pressure is 17500000 pa nd u knw p=hdg (d-density)
for oil da pressure will be p= x*830*g
nd for water its gonna be p= (2000-x)*1000*g
u knw p of oil + p of water = 17500000 pa hence equate p of oil nd p of water to 17500000
17500000 = (830gx) + (1000g(2000-x))
x= 1270m
hope u get it

 

[SalmanslK]

in Question 2 depths are equal hence we know, height will now be h/2 and mass will also be m/2.

hence PE= (m/2) . (g) . (h/2) = mgh/4

 

[leosco1995]

For question 1, the liquid pressure formula involves finding the height difference between the tubes. If you increase the RHS by 'x' metres, then the left hand side will decrease by 'x' metres and vice versa. It's sort of common sense really. If one part of the tube is going up, then the other part will go down.

So in this case, because the RHS increases by 'h' the LHS decreases by 'h'. Total height difference = 2h.

Pressure = ρ * g * 2h = 2ρgh.

 

[Nibz]

Question 2. Water level halves in tube X, therefore, height and mass halve too.
Potential energy lost = m/2 . h/2 . g
= mgh/4