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Flashcards in Physics Class 3 Deck (25)
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1

Heat vs Temperature

Heat is the transfer of non-mechanical energy between system & environment
- extensive property: depends on mass of material

Temperature is measure of average internal thermal energy of system
- intensive property: like density or colour

2

When does the temprature increase?

When you change the phase

3

Zeroth Law of Thermodynamics

When 2 substances are in contact, heat transfers between them until they achieve the same temperature (thermal equilibrium)

4

3 Modes of Heat transfer

1. Conduction - heat transfer through solids in contact
2. Convection - heat transfer through fluid circulation
3. Radiation - heat transfer by emission/absorption of electromagnetic energy

5

First law of thermodynamics

Internal energy of a closed system depends on how much heat energy is transferred into system & how much work system does on its surroundings

ΔE = Q - W

6

Ideal Gas Law

PV = nRT

7

Isochoric

constant volume
ΔV = 0

ΔE = Q

8

Isobaric

Constant pressure
ΔP = 0

ΔE = Q - PΔV

9

Isothermal

Constant temperature
ΔT = 0

10

Adiabatic

No heat transfer
ΔQ = 0

11

Pressure

Distribution of force over an area
Formula: P = F / A
Units: N/m^2 = Pa (pascal)

1 atm = 100 kPa = 1000 Pa = 760 torr = 760 mmHg

12

Second law of thermodynamics

Entropy of an isolated system either stays the same or increases during any thermodynamic process

13

What happens to entropy of closed system?

It can decrease if the entropy of its surrounding environment increases by a greater amount because it exchanges energy with the outside environment

14

What kind of system is the human body?

Open system because it exchanges ENERGY and MATTER with its outside environment

15

Density

Formula: ρ = m/v
Units: kg/ m^3

16

Weight of fluid

W = ρVg

17

Specific gravity

sp. gravity = p / pwater

ρwater = 1000 kg/m^3

18

Hydrostatic Gauge Pressure

- Pressure due to being immersed with fluid

Pgauge = ρfluid x g x Depth
Ptotal = Psurface + P gauge

19

Buoyant Force

Upward force exerted on object either partially or completely submerged in a fluid due to pressure difference between top & bottom of object (bottom pressure > top pressure)

20

Archimede's Principle

Magnitude of buoyant fore is equivalent to the weight of the fluid that's displaced by the object

Fb = ρfluid x Vsubmerged x g

21

Flow rate

volume of fluid moving through a particular cross-sectional area per unit time

Units: m^3/s
Formula: f = Av
* flow speed is constant

22

Continuity

For an incompressible fluid, density is constant so flow rate is constant

A1v1 = A2v2

23

Ideal Fluid Flow Factors

1. Incompressibility (density is constant)
2. Negligible Viscosity
3. Laminar flow
4. Flow rate is stead (closed system)

24

Bernoulli's equation

P1 + ρgy1 + 1/2pv^2 = P2 + ρgy2 + 1/2pv^2

Describes ideal fluid flow

25

Fluids flow from _____ pressure to _____ pressure

High to low pressure