1. 2nd Law of Thermodynamics:
HW 12-2 AND 12-3
Heat always flows from to
HOT
COLD
Heat transfer Khan IR Camera

2. Heat ≠ Temperature
Bozeman temp
Temperature : proportional to average kinetic energy of particles (Units: K (Kelvin) ; oC (Celcius)
Heat – energy that flows from a hotter object (higher temperature) to a colder object (lower temperature)
(Units: J (joule)
WORK HW 12-2

3. NO, values range from 5 to 15

4. 50 ÷ 5 = 10 J
KINETIC ENERGY

5. HEAT WILL FLOW FROM HOT (SYSTEM #1) TO COLD (SYSTEM #2)
#1: 30 ÷ 3 = 10
#1: 12 ÷ 3 = 4 10 4
#1; Higher Average KE
HOT TO COLD
HEAT WILL FLOW FROM HOT (SYSTEM #1) TO COLD (SYSTEM #2)

6. #1: 21 ÷ 3 = 7
#2: 21 ÷ 3 = 7 7 7
TEMPERATURE ARE EQUAL (SAME AVERAGE KE; THERMAL = HEAT EQUILIBRIUM = BALANCE ; TEMPERATURES ARE EQUAL

7. THERMAL EQUILIBRIUM

8. HW 12-3 CONCEPT OF HEAT

9. Is the amount of material (mass) important in heat transfer?
B) The cup will have the higher final temperature; Each individual molecule absorbs more energy

10. $1
$100

12. When same total amount of energy is distributed amongst a smaller number of molecules, each individual molecule receives more energy.
10 energy units
split 5 ways
10 Energy Units
split 2 ways
Link to video
Higher Temp, each molecule has more KE

13. Finish the rest of 12-3 CONTAINER #1 = $500 CONTAINER #1
CUP
BUCKET OF WATER

14. #1: 24 ÷ 6 = 4
#2: 12 ÷ 3 = 4 4 4 24 12
TEMPERATURES ARE SAME; SAME AVERAGE KINETIC ENERGY
CONTAINER #1 HAS STORED MORE TOTAL HEAT 24 vs 12

15. #1: 300 ÷ 3 = 100
#2: 500 ÷ 10 = 50
100 50
300
500
CONTAINER #1 ; HIGHER AVERAGE KINETIC ENERGY
CONTAINER #2 HAS STORED MORE TOTAL HEAT 500 vs 300

16. Do all objects absorb and store heat in the same way
Do all objects absorb and store heat in the same way? If both cars are left in the sun in the senior lot for the same amount of time will the interiors be at the same temperature at lunch time?
Black Porsche
White Porsche

17. Do both of these materials store heat in the same way?
Water
Rock

18. “s” is Specific Heat Capacity
s = amount of energy
needed to raise the temp of 1 g
of a substance by 1ºC.
H2O: s = 4.18 J/gºC
Rock: s = 0.6 J/gºC
How much energy in J must be added to 1 g of H2O to raise its temp by 1 oC?
How much energy in J must be added to 1 g of rock to raise its temp by 1 oC?
4.18 J
0.6 J

19. HW 12-3, #8 OCEAN (4.18 J/ goC) ROCK (0.6 J/ goC)
MORE energy must be absorbed to raise T.
MORE energy must be lost to lower T.
LESS energy must be absorbed to raise T.
LESS energy must be lost to lower T

20. HW 12-3, #9 COPPER (0.13 J/ goC) ALUMINUM (0.89 J/ goC)
Stores less energy when raising Temp;
Releases less energy when lowering Temp
Stores less energy when raising Temp;
Releases less energy when lowering Temp

21. ALUMINUM HAS HIGHER HEAT CAPACITY; Al HAS MORE HEAT ENERGY STORED at 100 oC THAN Cu. WATER ABSORBS MORE HEAT FROM Al AND REACHES HIGHER FINAL TEMP.

22. Q = s×m×ΔT Q = heat absorbed or lost +Q if absorbed, -Q if lost
Copy at bottom of p. 128; write equation on top of 129.
Q = s×m×ΔT
Q = heat absorbed or lost
+Q if absorbed, -Q if lost
m = mass in grams
ΔT = temperature change:
Δ T = Tfinal – Tinitial
s = specific heat capacity
units of s are J/gºC

23. EXAMPLE PROBLEM Q = 1.77 x 105 J Q = ? or x m = 454 g
Calculate J of energy required to heat 454 g of water from 5.4oC to 98.6 oC. s of H2O = 4.18 J/g oC.
Q = ? or x
m = 454 g
Ti = 5.4 oC ; Tf = 98.6 oC ; ∆T = Tf - Ti = =93.2 oC
Q = sm ∆T = (4.18 J/ g oC)(454 g)(93.2 oC)
Q = 1.77 x 105 J