Physics 6 Lesson 30: Summary of Chapter 2 Thermodynamics
1. Summary of theory Tóm
1.1. Review questions
a. How does the volume of substances change as the temperature increases and when the temperature decreases?
b. Which of the solids, liquids, and gases expands the most with heat and which expands with the least?
c. Can you find an example that shows that thermal expansion when resisted can cause great force?
The iron bars on the track often have a gap because being in the sun will make the iron bars expand, if there is no gap, it will bend the track, which can cause great force.
d. What phenomenon does thermometer work on? Name and state the uses of common thermometers in life.
Thermometers work based on the thermal expansion of substances.
Medical thermometer: Measure human body temperature
Alcohol thermometer: Measure the temperature of the Laboratory.
Mercury thermometer: Measures the temperature of objects.
e. Nomenclature of adaptations
f. Do different substances melt and solidify at the same definite temperature? What is this temperature called?
Different substances do not melt and solidify at the same definite temperature.
This temperature is called the melting or freezing point of the solid
g. During melting, does the temperature of the solid increase as we continue to heat it?
H. Do liquids evaporate at the same temperature? On what factors does the rate of evaporation of a liquid depend?
Liquids do not evaporate at the same definite temperature but at all temperatures.
Evaporation rate depends on: temperature, wind and open surface area.
i. At what temperature does a liquid, even with continued heating, not increase in temperature? What is the characteristic of liquid evaporation at that temperature?
At boiling temperature, the liquid will not increase even if it continues to boil.
Evaporation at this temperature has the characteristics of both evaporating into the air bubbles and evaporating on the liquid surface.
1.2.2. Application question
a. Why must there be bends on the steam pipeline (Figure 30.1)?
– Please redraw this pipe when the pipe heats up, cools down?
The steam pipeline must have bends so that when it heats up and cools down, the pipe can expand easily without being obstructed.
When the pipe heats up
b. Use the data in Table 30.1 to answer the following questions:
c. Figure 30.3 plots the water temperature change over time.
Answer the questions:
– The segments BC and DE correspond to which process?
In segments AB and CD, what form does water exist in?
– The segments BC and DE correspond to the processes:
– In segments AB and CD, water exists in the following forms:
AB: solid state
2. Illustrated exercise
Question 1: At what temperature does a liquid, even with continued heating, not increase in temperature? What is the characteristic of liquid evaporation at this temperature?
At boiling point, the temperature of the liquid does not change even if the heating is continued.
At this temperature, the liquid evaporates both inside and on the surface of the liquid, creating air bubbles in and on the surface of the liquid.
Verse 2: Does a liquid evaporate at a definite temperature? On what factors does the rate of evaporation of a liquid depend?
Liquids evaporate at all temperatures.
The rate of evaporation depends on the temperature, wind and open surface of the liquid.
3.1. Essay exercises
Question 1: The three thermometers have three temperature scales respectively: Xenxiut, Farenhai and Kevin. We use those three thermometers to measure the temperature of the water tank. Ask:
a) When the Celsius scale is only 30 thangoC, what is the value of the Farenhai temperature scale and the Kelvin temperature scale?
b) When heating the flask increases by 20oC, how much does the Farenhai temperature scale and the Kevin temperature scale increase?
Verse 2: The medical thermometer has a measurement limit on the Xenxiut temperature scale from 35oC to 4oC. If calculated according to the Farenhai temperature scale, what is the measurement limit of that thermometer?
Question 3: Know when the temperature rises from 20oC to 50oC, 1 liter of water expands by 10.2 cm3. So 2000 cm3 of water is initially at 20oC when heated to 50oWhat volume will C have?
Verse 4: A flask of ether, a flask of wine and a flask of water have the same volume of 1 liter at 0 .oC, when heating all three flasks up to 50oC, we see that the liquid level in the three tanks shows the values respectively: 1080 cm3, 1058 cm3 and 1012 cm3. What is their increase in volume? From this, it is inferred which of the three substances expands more because of heat. Let’s sort in ascending order.
3.2. Multiple choice exercises tập
Question 1: Which of the following is true when comparing the thermal expansion of gases and solids?
A. Gases expand because of less heat than solids.
B. Gases expand more because of heat than solids.
C. Gases and solids expand because of heat in the same way.
D. All three of the above conclusions are wrong.
Verse 2: Select the correct answers.
A. As the temperature decreases, the specific gravity of the gas decreases.
B. As the temperature increases, the specific gravity of the gas increases.
C. When the temperature increases or decreases, the specific gravity of the gas does not change.
D. As the temperature increases, the specific gravity of the gas decreases.
Question 3: Temperature 50oC corresponds to how many degrees Farenhai?
A. 82oF B. 90oF
C. 122oF D. 107.6oF
Verse 4: Which of the following is characteristic of boiling?
A. Occurs at any temperature.
B. The temperature remains constant during boiling.
C. Occurs only in the open surface of the liquid.
D. There is a transition from liquid to solid.
Through this lecture summarizing chapter 2- Thermodynamics, students need to complete some of the objectives given by the lesson, such as:
Consolidate and firmly grasp the basic knowledge of Chapter 2.
Applying a synthesis of learned knowledge to solve problems (Answering questions, solving exercises, explaining phenomena…) are related.