Lecture 18

Lecture 18 Calendar
Lecture 17. Rotational KE and Angular Momentum

PHYS 1750: SELECTED TOPICS in PHYSICS
LECTURE 18. Fluids.

10.1. Solids, Liquids, Gasses

1. Atoms, molecules, and little 'springs'

2. Crystalline and amorphous solids

3. Liquids and gasses

10.2. Density

1. ρ = m /V kg /m³

water = 1000 kg /m³

2. Some densities of materials: A table in grams /cc. Multiply by 1000 for kg /m³

10.3. Pressure

1. Force per unit area: P = F/A
Newtons /m² = Pascals

2. Always perpendicular to any surface, real or imagined.

10.4. Hydrostatic Equilibrium

1. Nothing moves (equilibrium)

2. Pressure is constant on level surfaces (or there would be flow)

3. At any depth, upward pressure*A must = weight mg of material above A

a. Assume density ρ nearly constant above A

b. Then m (above A) = ρAh, where h is the depth

c. So P = ρgh

4. Standard air pressure = 1 atm = 1.01×10⁵ Pa

Q: How many kg of air are above every square meter at sea level?

Review Questions are linked in the next lecture.
Lecture 19: Some Fluid Principles

10.1.	Solids, Liquids, Gasses
	1.	Atoms, molecules, and little 'springs'
	2.	Crystalline and amorphous solids
	3.	Liquids and gasses
10.2.	Density
	1.	ρ = m /V kg /m³
		water = 1000 kg /m³
	2.	Some densities of materials: A table in grams /cc. Multiply by 1000 for kg /m³
10.3.	Pressure
	1.	Force per unit area: P = F/A Newtons /m² = Pascals
	2.	Always perpendicular to any surface, real or imagined.
10.4.	Hydrostatic Equilibrium
	1.	Nothing moves (equilibrium)
	2.	Pressure is constant on level surfaces (or there would be flow)
	3.	At any depth, upward pressure*A must = weight mg of material above A
		a. Assume density ρ nearly constant above A
		b. Then m (above A) = ρAh, where h is the depth
		c. So P = ρgh
	4.	Standard air pressure = 1 atm = 1.01×10⁵ Pa
		Q: How many kg of air are above every square meter at sea level?