What is pressure??

UNDERSTANDING PRESSURE IN LIQUID

By The end of this lesson, you should be able to :-

Relate depth to pressure in a liquid. Relate density to pressure in a liquid. Explain pressure in a liquid and state p = hρg

Learning Outcome :

• Students do activity to determine relationship between pressure in liquid relate to depth.

• Students will be given worksheet and solve 4 numerical problems.

Activities :

How does pressure in liquid relate to depth?

How does pressure in liquid relate to density?

What is the relationship between gravitational field strength and pressure?

Liquid pressure increases as the gravitational field strength increases

Relating Pressure (p) in a liquid to the Depth (h) and Density

p = hρg

SI unit => pascal (Pa) or Nm-2

Worksheet :

TOPIC : PRESSURE IN LIQUID

The diagrams show two divers swimming in sea water and two divers swimming in fresh water

1. Between divers A and B, who experienced greater pressure? Why?

Answer:

Diver B, because B divers deeper than A.

2. Between divers B and D, who experienced greater pressure? Why?

Answer:

Diver B, because sea water is denser than fresh water

3. Calculate the liquid pressure exerted on divers A and D

Given: The density of sea water = 1150 kgm-3

The density of fresh water = 1000 kgm-3

Gravitational field strength = 10 Nkg-1

Answer:

Liquid pressure on diver A

p = ρhg = (1150)(2)(10) = 2.3 x 104 Pa

Liquid pressure on diver D

p = ρhg = (1000)(6)(10) = 6 x 104 Pa

4. Arrange in descending order the strength of the liquid pressure exerted on the divers A, B, C and D.

Answer:

diver B > diver D > diver A > diver C

By The end of this lesson, you should be able to :-

Relate depth to pressure in a liquid. Relate density to pressure in a liquid. Explain pressure in a liquid and state p = hρg

Learning Outcome :

The pressure at any point in a liquid at rest is directly proportional to :-

a) the dept of the liquid, hb) the liquid density, ρc) the gravitational filed strength, g

Conclusion :

Textbook ; page 78 Exercise 3.2 Question 1 – 3

Read Practical Book Page 49

Homework :

Understanding Gas Pressure

What is gas pressure???How to measure gas pressure??

Next Lesson :