Question

Hello :) how to do this qn?

Answer 1

Answer:

A

Explanation:

When we see a U- tube manometer, the first concept that we should think about is pressure. This is because manometers are used to measure pressure.

Any point of the manometer at the same vertical height has the same pressure. Thus, if we look at the dotted line in the diagram, the pressure is equal at any point along that line. Let's compare both sides of the manometer with each other.

Fluid pressure (P)

P= ρgh,

where ρ= density of the fluid,

g= acceleration due to gravity,

h= height of fluid

Pressure is defined as the amount of force exerted per unit area. Thus, pressure along the dotted line in the manometer is due to the force exerted by the column of fluid above it, as well as the force exerted by the atmospheric pressure. We can disregard the force due to atmospheric pressure since the atmospheric pressure exerted on both sides of the manometer is the same.

Pressure due to water= pressure due to oil

1(g)(8)= ρ(g)(10)

The value of g would be the same on the right and left side of the manometer and hence we can cancel it out.

8= 10ρ

ρ= 8 ÷10

ρ= 0.8 g/cm³

Answer 2

The answer is B because oil = blockage of air and it pressures the water to be density of 0.90