Some pressure concepts i don't understand

[benedict9999]

Homework Statement

The pressure at 10 m below the surface of the ocean is about 2.00×10^5 Pa.

Which of the following statements is true?

a. The weight of a column of seawater 1 m^2 in cross section and 10 m high is about 2.00×10^5 N.
b. The weight of a column of seawater 1 m^2 in cross section and 10 m high plus the weight of a column of air with the same cross section extending up to the top of the atmosphere is about 2.00×10^5 N.
c. The weight of 1 m^3 of seawater at 10 m below the surface of the ocean is about 2.00×10^5 N.
d. The density of seawater is about 2.00×10^5 times the density of air at sea level.

I may sound a bit greedy but if you can please explain why it is that and why others aren't right

 

[tiny-tim]

Welcome to PF!

Hi benedict9999! Welcome to PF!

I may sound a bit greedy but if you can please explain why it is that and why others aren't right

No, you first!

Tell us which one you think it is, and why.

( Start with the definition of pressure )

 

[tomcue]

.

I am happy to provide an explanation for these pressure concepts. Let's start with the given statement, which states that the pressure at 10 m below the surface of the ocean is about 2.00×10^5 Pa. This means that at this depth, the water is exerting a force of 2.00×10^5 N on every square meter of surface area.

Now, let's look at the given options and determine which one is true.

a. The weight of a column of seawater 1 m^2 in cross section and 10 m high is about 2.00×10^5 N.

This statement is true because the pressure at a certain depth is equal to the weight of the water above that depth. In this case, the weight of the water above a 1 m^2 column at 10 m depth is equal to the pressure at that depth, which we know is 2.00×10^5 N.

b. The weight of a column of seawater 1 m^2 in cross section and 10 m high plus the weight of a column of air with the same cross section extending up to the top of the atmosphere is about 2.00×10^5 N.

This statement is not true. The pressure at a certain depth is only influenced by the weight of the fluid above that depth. The weight of the air above the water does not contribute to the pressure at 10 m depth.

c. The weight of 1 m^3 of seawater at 10 m below the surface of the ocean is about 2.00×10^5 N.

This statement is also not true. While the weight of a column of water is equal to the pressure at a certain depth, the weight of a 1 m^3 volume of water is not the same as the weight of a column of water with a 1 m^2 cross section.

d. The density of seawater is about 2.00×10^5 times the density of air at sea level.

This statement is not true. While seawater is denser than air, the difference in density is not on the order of 2.00×10^5. The density of seawater at 10 m depth is approximately 1025 kg/m^3, while the density of air at sea level is approximately 1.2 kg/m^3.