FQ - 2B - 17 de marzo de 2022

FQ - 2B
- repeat last class
- thermal expansion
- thermal equilibrium
- make exercises
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Slide 1: Tekstslide
Natuurkunde / ScheikundeMiddelbare schoolhavoLeerjaar 2

In deze les zitten 12 slides, met tekstslides en 1 video.

Onderdelen in deze les

FQ - 2B
- repeat last class
- thermal expansion
- thermal equilibrium
- make exercises

Slide 1 - Tekstslide

Repetition
What is:
  • kinetic energy
  • thermal energy
  • absolute zero
  • heat
  • What happens when adding heat?
  • What is the relation between Kelvin and Celsius?

Slide 2 - Tekstslide

Which one has more kinetic energy?

Slide 3 - Tekstslide

What is the temperature?
80 °C
20 °C

Slide 4 - Tekstslide

Thermal extension
Listen carefully to the video.

Slide 5 - Tekstslide

Slide 6 - Video

Expansion in solids and liquids

linear expansion:
L = L0 (1 + α x ΔT)

L = length of the bar
L0 = initial length before heating
α = coefficient of linear expansion
ΔT = variation in temperature

Expansion in gases

Charles' Law
V = k x T
k = proportionality constant

Remember that the temperature is given in Kelvin when you make calculations using Charles' Law


Slide 7 - Tekstslide

Thermal equilibrium
= When two fysical bodies or systems at different temperatures come into contact, they end up having the same temperature

Heat is the transfer of energy from one body or
system with higher temperature to antoher with
a lower temperature.

Slide 8 - Tekstslide

Measurement of heat
Heat is measured in units of energy → joule (J).

Traditional unit is the calorie (cal). A calorie is defined as the amount of heat needed to heat a gram of water by one degree.

1 cal = 4,184 J

Slide 9 - Tekstslide

Let's practise
Make exercises 5 through 11.

Finished? Process the theory.

Slide 10 - Tekstslide

Answers
5. Alcohol, because the linear expansion coefficient is highest.
6. L = 1000 (1 + 1,1 * 10-5 x 40) = 1000,44 m, so it has expanded
     0,44 m or 44 cm.
7. If they didn't use expansion joints, there could be potential distortion or breaks.
8. The flame is to heat the helium gas. This way the gas expands and the balloon goes up in the air.

Slide 11 - Tekstslide

Answers
9. 
                                                       V1 = (1 x 300) / 20 = 15 m3

10. a) 20 cal = 83,68 J                                  d) 4200 kJ = 1004 kcal
     b) 3000 J = 717 cal                                   e) 5000 cal = 1,195 kJ
     c) 1500 kcal = 6276 kJ                            f) 16400 J = 3,919 kcal
1 m3
V1
20 °C
300 °C

Slide 12 - Tekstslide