Question

At a fixed depth within a fluid at rest, the pressure pushing upward is

A) less than the pressure pushing downward.

B) zero, because pressure only pushes equal in all horizontal direction

C) zero, because the fluid above does not support the weight of the fluid below

D) greater than the pressure pushing downward

E) equal to the pressure pushing downward

Salt water has greater density than fresh water. A boat floats in both fresh water and salt water. Where is the buoyant force greater on the boat?

A) salt water.

B) fresh water.

C) Buoyant force is the same in both.

D) Cannot be determined from the information given

Answer 1

Answer: E) A) salt water.

Step-by-step explanation:

E) In equilibrium, pressure exerts equally in all directions, so for a given depth, the pressure is the same for all points located at the same depth, and it can be written as follows:

p = p₀ + ρ.g.h, where p₀ = atmospheric pressure, ρ=fluid density, h=depth from the surface.

A) The buoyant force, as discovered by Archimedes, is an upward force, that opposes to the weight of an object (as it is always downward), and is equal to the weight of the volume of the liquid that the object removes, which means that is proportional to the density of the liquid.

As salt water is denser than fresh water, the buoyant force exerted by the salt water is always greater than the one produced by the fresh water, so objects will float more easily in salt water than in fresh water.

In the limit, it is possible that one object float in salt water and sink in fresh water.