JPN Pahang Physics Module Form 4 Student’s Copy Chapter 4: Heat 86 4.1 : UNDERSTANDING THERMAL EQUILIBRIUM By the end of this subtopic, you will be able to Explain thermal equilibrium Explain how a liquid-in glass thermometer works 1. The net heat will flow from A to B until the temperature of A is the ( same, zero as the temperature of B. In this situation, the two bodies are said to have reached thermal equilibrium. 2. When thermal equilibrium is reached, the net rate of heat flow between the two bodies is (zero, equal) 3. There is no net flow of heat between two objects that are in thermal equilibrium. Two objects in thermal equilibrium have the ……………… temperature. 4. The liquid used in glass thermometer should (a) (b) (c) 5. List the characteristic of mercury (a) (b) (c) (d) (e) Thermal equilibrium :Keseimbangan terma CHAPTER 4: HEAT …………………………………………………………………………….. ………………………………………………………………………………. …………………………………………………………………………….. …………………………………………………………………………………….. ……………………………………………………………………………………. ……………………………………………………………………………………. ……………………………………………………………………………………. ……………………………………………………………………………………. ………….. rate of energy transfer Hot object Cold object ………….. rate of energy transfer Equivalent to Equivalent to No net heat transfer A B
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JPN Pahang Physics Module Form 4
Student’s Copy Chapter 4: Heat
86
4.1 : UNDERSTANDING THERMAL EQUILIBRIUM
By the end of this subtopic, you will be able to
Explain thermal equilibrium
Explain how a liquid-in glass thermometer works
1. The net heat will flow from A to B until the temperature of A is the ( same, zero as the
temperature of B. In this situation, the two bodies are said to have reached thermal
equilibrium.
2. When thermal equilibrium is reached, the net rate of heat flow between the two bodies is
(zero, equal)
3. There is no net flow of heat between two objects that are in thermal equilibrium. Two
objects in thermal equilibrium have the ……………… temperature.
4. The liquid used in glass thermometer should
(a) Be easily seen
(b) Expand and contract rapidly over a wide range of temperature
(c) Not stick to the glass wall of the capillary tube
5. List the characteristic of mercury
(a) Opaque liquid
(b) Does not stick to the glass
(c) Expands uniformly when heated
(d) Freezing point -390C
(e) Boiling point 3570C
Thermal equilibrium
:Keseimbangan terma
CHAPTER 4: HEAT
……………………………………………………………………………..
……………………………………………………………………………….
……………………………………………………………………………..
……………………………………………………………………………………..
…………………………………………………………………………………….
…………………………………………………………………………………….
…………………………………………………………………………………….
…………………………………………………………………………………….
…………………………………………………………………………………….
………….. rate of energy transfer
Hot
object
Cold
object
………….. rate of energy transfer
Equivalent to Equivalent to
No net heat transfer
A B
JPN Pahang Physics Module Form 4
Student’s Copy Chapter 4: Heat
87
6. ( Heat, Temperature ) is a form of energy. It flows from a hot body to a cold body.
7. The SI unit for ( heat , temperature) is Joule, J.
8. ( Heat , Temperature ) is the degree of hotness of a body
9. The SI unit for (heat , temperature) is Kelvin, K.
10. Lower fixed point (l 0 )/ ice point : the temperature of pure melting ice/00C
11. Upper fixed point( l 100)/steam point: the temperature of steam from water that is boiling
under standard atmospheric pressure /1000C
Exercise 4.1
Section A: Choose the best answer
1. The figure shows two metal blocks.
Which the following statement is
false?
A. P and Q are in thermal contact
B. P and Q are in thermal equilibrium
C. Energy is transferred from P to Q
D. Energy is transferred from Q to P
2. When does the energy go when a cup
of hot tea cools?
A. It warms the surroundings
B. It warms the water of the tea
C. It turns into heat energy and
disappears.
3. Which of the following temperature
corresponds to zero on the Kelvin
scale?
A. 2730 C
B. 00C
C. -2730 C
D. 1000 C
4. How can the sensitivity of a liquid- in
–glass thermometer be increased?
……………………………..…
…………………………………
l0 : length of mercury at ice point
l100 : length of mercury at steam point
lθ : length of mercury at θ point
Temperature, θ = lθ - l0
l100 - l0 x 100
0C
JPN Pahang Physics Module Form 4
Student’s Copy Chapter 4: Heat
88
A. Using a liquid which is a better
conductor of heat
B. Using a capillary tube with a
narrower bore.
C. Using a longer capillary tube
D. Using a thinner-walked bulb
5. Which instrument is most suitable for
measuring a rapidly changing
temperature?
A. Alcohol-in –glass thermometer
B. Thermocouple
C. Mercury-in-glass thermometer
D. Platinum resistance thermometer
6. When shaking hands with Anwar,
Kent Hui niticed that Anwar’s hand
was cold. However, Anwar felt that
Kent Hui hand was warm. Why did
Anwar and Kent Hui not feel the
same sensation?
A. Both hands in contact are in
thermal equilibrium.
B. Heat is flowing from Kent Hui’s
hand to Anawr’s hand
C. Heat is following from Anwar’s
hand to Kent Hui hand.
Section B: Answer all the questions by showing the calculation
1. The length of the mercury column at the ice point and steam point are 5.0 cm and 40.0cm
respectively. When the thermometer is immersed in the liquid P, the length of the mercury
column is 23.0 cm. What is the temperature of the liquid P?
2. The length of the mercury column at the steam point and ice point and are 65.0 cm and
5.0cm respectively. When the thermometer is immersed in the liquid Q, the length of the
mercury column is 27.0 cm. What is the temperature of the liquid Q?
Temperature, θ = lθ – l0 x 1000C
l100 – l0
θ = 27 – 5 x 1000C
65 - 5
θ = 36.670C
JPN Pahang Physics Module Form 4
Student’s Copy Chapter 4: Heat
2
3. The distance between 00C and 100
0C is 28.0 cm. When the thermometer is put into a
beaker of water, the length of mercury column is 24.5cm above the lower fixed point. What
is the temperature of the water?
4. The distance between 00C and 100
0C is 25 cm. When the thermometer is put into a beaker
of water, the length of mercury column is 16cm above the lower fixed point. What is the
temperature of the water? What is the length of mercury column from the bulb at
temperatures i) 300C
JPN Pahang Physics Module Form 4
Student’s Copy Chapter 4: Heat
3
SECTION C: Structured Questions
1. Luqman uses an aluminium can, a drinking straw and some plasticine to make a simple
thermometer as shown in figure below. He pours a liquid with linear expansion into the
can.
(a) Suggest a kind of liquid that expands linearly. (1m)
…………………………………………………………………………………………….
(b) He chooses two fixed points of Celsius scale to calibrate his thermometer. State them
(2m)
………………………………………………………………………………………………
………………………………………………………………………………………………
(c) If the measurement length of the liquid inside the straw at the temperature of the lower
fixed point and the upper fixed point are 5cm and 16 cm respectively, find the length of
the liquid at 82.50C.
(d) Why should he use a drinking straw of small diameter?
………………………………………………………………………………………………
(e) What kind of action should he take if he wants to increase the sensitivity of his
thermometer?
………………………………………………………………………………………………
………………………………………………………………………………………………
JPN Pahang Physics Module Form 4
Student’s Copy Chapter 4: Heat
4
2. What do you mean by heat and temperature?
……………………………………………………………………………………………....
………………………………………………………………………………………………
………………………………………………………………………………………………
: UNDERSTANDING SPECIFIC HEAT CAPACITY
By the end of this subtopic, you will be able to
Define specific heat capacity
State that c = Q/MCθ
Determine the specific heat capacity of a liquid
Determine the specific heat capacity of a solid
Describe applications of specific heat capacity
Solve problems involving specific heat capacity
1. The ……………….. of a body is the …………………….. that must be supplied to the
body to increase its temperature by 10C.
2. The heat capacity of an object depends on the
(a) ……………………………………………………………………………………….
(b) ……………………………………………………………………………………….
(c) ………………………………………………………………………………………
3. The ………………………of a substance is the amount of heat that must be supplied to
increase the temperature by 1 0C for a mass of 1 kg of the substance. Unit Jkg
-1 K
-1
4. The heat energy absorbed or given out by an object is given by Q = mc∆O.
5. High specific heat capacity absorb a large amount of heat with only a
……………temperature increase such as plastics.
Heat capacity
Muatan haba
Specific heat capacity
Muatan haba tentu
Specific heat capacity , c = Q__
m∆θ
JPN Pahang Physics Module Form 4
Student’s Copy Chapter 4: Heat
5
6. Conversion of energy
7. Applications of Specific Heat Capacity
Explain the meaning of above application of specific heat capacity: