4.3 Forces, Density, and Pressure

Question 1

4.3.1 What is the relationship between density, mass, and volume, and then define density:

Answer 1

ρ = m/V
ρ = density in kgm^-3
m = Mass in kg
V = Volume in m^3

Density is the mass per unit volume.

Question 2

4.3.2 What is the relationship of pressure, area, and force, and then define pressure:

Answer 2

P = F/A
P = Pressure in Pa
F = Force in N
A = Area in m^2

Pressure is the force per unit area.

Question 3

4.3.4 What is the equation for hydrostatic pressure and units

Answer 3

ΔP = ρgh
ΔP = Change in hydrostatic pressure in Pa
ρ = Density in kgm^-3
g = Gravitational field strength/ acceleration due to gravity in ms^-2
h = Change in height in m

Question 4

4.3.5 Why does upthrust act on an object in a fluid?

Answer 4

It is due to a difference in hydrostatic pressure.

Question 5

What is upthrust?

Answer 5

Upthrust is a force which pushes upwards on an object submerged in a fluid i.e. liquids and gases