Chapter 4: Density and Pressure

Question 1

What is the equation relating density, mass and volume?

Answer 1

density = mass/volume

Question 2

What is density measured in?

Answer 2

g/cm^3 or kg/m^3

Question 3

What is the equation linking pressure, force and area?

Answer 3

pressure = force/area

Question 4

What is pressure measured in?

Answer 4

Pa (1N/m^2) or N/cm^2

Question 5

In what direction does pressure in a fluid act?

Answer 5

All directions

Question 6

What factors affect pressure in a fluid?

Answer 6

The depth and density increase the pressure in a fluid. Surface area has no effect.

Question 7

What is the equation to find the pressure in a fluid?

Answer 7

Pressure = mass x gravity x height/depth

Question 8

How do you find the density of a regular shaped block?

Answer 8

Weigh the block using an electronic scale. Calculate the volume by measuring the sides and multiplying.

Question 9

How do you find the density of an irregular shaped block?

Answer 9

Weigh the block using an electronic scale. Put the block in a known volume of water. The volume of water displaced is equal to the volume of the block.

Question 10

How does an object exert pressure on the ground in terms of force and area?

Answer 10

Even if the force is small, if the area is small, then the pressure will be large, and so it can be more dangerous. A large force exerted over a large area can have a lower pressure.

Question 11

Why can’t you have a long snorkel? (Example)

Answer 11

Lungs cannot expand because the pressure of the water is too high.