Mechanical Properties of Fluids Test - 2

fluids can flow due to unbalanced forces between the atoms of fluids.

Density is defined as the compactness of substance.

Mathematically,

Density(D) = Mass(M) / Volume(V)

The specific gravity of an object is the ratio between the density of an object to a reference liquid. Usually, this reference liquid is water, which has a density of 1 g/mL or 1 g/cm^3.

Water has a specific gravity equal to 1. Materials with a specific gravity less than 1 are less dense than water, and will float on the pure liquid; substances with a specific gravity more than 1 are more dense than water, and will sink.

 It is important to note that it is valid only for a fluid at rest. In the case of a moving fluid, pressures in different directions could be different depending upon fluid accelerations in different directions. 

According to Pascal's Law,

P-P₀ = hdg

from above

Change in pressure is directly proportional to depth from the free surface.

At the same horizonatal line all point are at the same depth and have same value of acceleration due to gravity and denity of water as well.

According to Pascal's Law,

Change in Pressure (P-P₀) = hρg

if h=0 then P-P₀ = 0

and P=P₀

The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N/m², or kg. m. s⁻²). This name for the unit was added in 1971; before that, pressure in SI was expressed simply in newtons per square metre

Gauge pressure is zero-referenced against ambient air pressure, so it is equal to absolute pressure minus atmospheric pressure. Negative signs are usually omitted

The difference between absolute pressure and atmospheric pressure is what we call gauge pressure (P_gauge). It can be calculated if we know the absolute and atmospheric pressures using this formula: 

P_gauge = P_abs − P_atm

Pascal's principle is defined as a change in pressure at any point in an enclosed fluid at rest is transmitted undiminished to all points in the fluid.

This principle is stated mathematically as:
ΔP = ρg(Δh)

ΔP is the hydrostatic pressure (given in pascals in the SI system), or the difference in pressure at two points within a fluid column, due to the weight of the fluid.