Question

physics question please answer fast

Answer 1

So the pressure below the water at a certain height 'h' is thrice the atmospheric pressure.

The atmospheric pressure is given as,

P_0 = 10 N cm^(-2).

But,

1 cm = 10^(-2) m

1 cm^(-2) = [10^(-2)]^(-2) m^(-2)

1 cm^(-2) = 10^4 m^(-2)

Thus, the atmospheric pressure is 10 × 10^4 = 10^5 N m^(-2).

P_0 = 10^5 N m^(-2)

So the pressure inside the water under the height 'h' is,

P' = 3 × 10^5 N m^(-2).

And, given,

g = 9.8 m s^(-2)

ρ = 10^3 kg m^(-3)

We have the expression for the pressure inside the water, P'.

Pressure under the surface of water = Atmospheric pressure + Pressure due to water column

P' = P_0 + P → (1)

And, we know the expression for the pressure due to water column, or, hydrostatic pressure.

P = ρgh

Then, (1) becomes,

3 × 10^5 = 10^5 + ρgh

ρgh = 2 × 10^5

10^3 × 9.8 h = 2 × 10^5

h = 200 / 9.8

h = 20.4 m

Thus the pressure under the surface of the water at a depth 20.4 m is thrice the atmospheric pressure.