physics ii phy 202/222 temp, heat & gas laws 452 south anderson road rock hill, sc 29730
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Physics II PHY 202/222
Temp, Heat & Gas Laws
452 South Anderson Road
Rock Hill, SC 29730
www.yorktech.com
Temp, Heat & Gas Laws Test 2
Beiser Chapters 18, 19 & 22- Multiple Choice – Odd
- Supplementary Problems - Odd
Browne Chapter 17 for PHY 221 Students
- Supplementary Problems - 4,5,10,14
Beiser Chapter 18 - Heat
Beiser p.213
Stuff
Remember: All matter is composed of molecules which are moving rapidly. Since these molecules are moving and have mass, they have kinetic energy!
Beiser p.213
Definitions
• Internal Energy – sum of the kinetic energies of molecules of matter
• Temperature – measure of average kinetic energy of molecules
• Heat – internal energy in transit
• Thermometer – a device to measure temperature
Beiser p.213-4
CelsiusKelvin
(Celsius +273)Fahrenheit
Water freezes
0oC 273 K 32oF
Water boils
100oC 373 K 212oF
F C
C F
9T T 32
55
T (T 32)9
T
Beiser p.214
Temperature Scales
QUnits of heat
• Joule - SI unit
• Calorie (cal) - heat needed to raise 1 g of water 1oC
• Kilocalorie (kcal) – heat needed to raise 1 kg of water 1oC (same as calorie in food info)
• 1 kcal = 1000 cal
Beiser p.214
Heat (Internal energy in transit)
Q“British” Units of heat
• British Thermal Units (BTU) – heat needed to raise 1 lb of water 1oF
• 1 kcal = 3.97 BTU = 4185 J
Beiser p.214
Heat
CJ/(kg oC)
cal/(g oC) or
kcal/(kg oC)
Water 4187 1.00
Ice 2090 0.5
Wood 1700 0.4
Aluminum 900 0.215
Glass 840 0.200
Iron 448 0.107
Copper 390 0.0920
How much energy does it take to change the temperature of the material.
Beiser p.214
Specific Heat Capacity
Beiser p.216-7
Change of State
Calorimetry
• Sensible heat – adding heat raises temperature
• Latent heat – adding heat changes state
Q mc T
Q m LBeiser p.215-7
• How much heat will it take to melt 2 kg of ice?
• How much heat will it take to raise the temperature of 2 kg of water by 17o C?
• How much heat will it take to melt 2 kg of ice and raise the temperature to 17o C?
Calorimetry example
fQ m L 2kg(335kJ / kg) 670kJ
o o
Q m c T
2kg(4.185kJ / kg C)(17 C) 142kJ
TotalQ 670kJ 142kJ 812kJ
670 kJ
142 kJ
Beiser p.215
Mixing problemAdd 200 g of iron at 100oC to 600 g of water at 20oC. Find the final
temperature.
water water water bar bar bar
o oo o
o
o
Heat gained by water = Heat lost by bar
m c T m c T
kJ kJ(.6kg)(4.185 )(T 20 C) (.2kg)(.448 )(100 C T)
kg C kg C
2.51T 50.22 8.96 .09T
2.56T 59.18 C
T 23.1 C
Beiser p.216
18.4
18.6
18.8
18.10
18.12
18.14
18.16
18.18
18.20
18.22
18.24
Beiser p.224
Beiser Chapter 19Thermal Expansion
OL a L T
LO
ΔL
ΔT
Beiser p.224
Linear Expansion
OV b V T
VO V = VO + ΔV
ΔT
Beiser p.224
Volume Expansion
1 1 2 2p V p V when T is constant
V1 ΔT= 0
V2
P1
P2
As volume goes up, pressure goes down to keep the product constant.
Beiser p.226
Boyle’s Law
1 2
1 2
V Vwhen p is constant
T T
V1 Δp = 0
V2
T1
T2
As volume goes up, temperature drops. T must be in K!
Beiser p.227
Charles’s Law
V1V2
P1 P2
Volume, pressure and temperature are all related by the Ideal Gas Law.
Beiser p.228
1 1 2 2
1 2
p V p V
T T
T1 T2
The Ideal Gas Law
19.2
19.4
19.6
19.8
19.14
19.16
Beiser p.259
Chapter 22Heat Transfer
Beiser p.259
Q k A T
t d
Rate of Heat Conduction
Heating by contact/collisions between molecules.
Q heatt timek thermal conductivity - look upA cross section areaΔT ΔT from 1 hot to cold sided length/thickness of material
Beiser p.260
d thicknessR
k thermal conductivity
Thermal Resistance
Material k (W/m oC)
Air .026
Wood 0.12
Water 0.61
Glass 0.8
Iron 80.3
Aluminum 237
Copper 398
Silver 427
Beiser p.261
Qh A T
t
ConvectionHeating by motion of a hot fluid.
Q heatt timeh factor will be givenA area of contact hot to fluidΔT ΔT between hot and fluid
Beiser p.262
4PR e T
A
RadiationHeating by energy from electro-magnetic waves.
R rate of radiationP power emittedA surface areaT temperatureσ = 5.67 E-8 W/(m2K4)e emissivity 0 total reflection 1 blackbody/total absorption 0<e<1 will be given
Stefan-Boltzmann Law
22.4
22.6
22.10