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# 4.0 heat

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### 4.0 heat

1. 1. Physics Module Form 4 Chapter 4 - Heat GCKL 2010 4.14 UNDERSTANDING THERMAL EQUILIBRIUM What is thermal equilibrium ? 1. (______, Temperature ) is a form of energy that flows from a hot body to a cold body. 2. The SI unit for (______, temperature) is Joule, J. 3. ( Heat , _____________ ) is the degree of hotness of a body 4. The SI unit for (heat , ___________) is Kelvin, K. 5. When thermal equilibrium is reached, the net rate of heat flow between the two bodies is (______, equal) 6. There is no net flow of heat between two objects that are in thermal equilibrium. Two objects in thermal equilibrium have the …______ … temperature irrespective of shape, mass, size or type of surface.Calibration ofthermometer 7. The ______ ______ of an object is important in the construction of a thermometer. It is a physical quantity which is sensitive to and changes linearly with the change in temperature of the object. 4-1
2. 2. Physics Module Form 4 Chapter 4 - Heat GCKL 2010 8. ________________ (l 0 )/ ice point : the temperature of pure melting ice/00C 9. ________________ ( l 100)/steam point: the temperature of steam from water that is boiling under standard atmospheric pressure /1000C 10. The lengths of the mercury column in the mercury-in-glass thermometer is 2.6 cm at 0OC and 22.6 cm at 100OC. When the thermometer is placed in hot water, the length of the mercury column is 16.9 cm. Calculate the temperature of the hot water. Answer :Liquid-in-glass 11. The liquid used in glass thermometer shouldthermometer (a) Be easily ______ (b) Expand and contract rapidly over a ______ range of temperature (c) Not ______ to the glass wall of the capillary tube 12. List the characteristic of mercury (a) ______ liquid (b) Does not ______ to the glass (c) ______ uniformly when heated (d) ______ point -390C (e) ______ point 3570C 13. Which modification increases the sensitivity of the thermometer ? A. Increasing the size of the bulb B. Increasing the thickness of the bulb C. Reducing the diameter of the capillary tube D. Reducing the length of the capillary tube 4-2
3. 3. Physics Module Form 4 Chapter 4 - Heat GCKL 2010Check Yourself 1 1. The diagram below shows a thermometer is used to measure the temperature of hot water. When the thermometer and the hot water are in thermal equilibrium, which of the following is not correct ? 4. Diagram below shows the liquid levels from the bulb in three thermometers P, Q and R at certain temperatures.A. The temperature of hot water is equal to the temperature of the thermometerB. No heat flow between thermometer and hot waterC. Heat flows from hot water to thermometerD. Heat flows from thermometer to hot water2. Which of the following characteristics does a liquid-in-glass thermometer work ? What is the temperature reading atA. Volume of a fixed mass of liquid thermometer R ?B. Length of the liquidC. Resistance of the liquid A. 70.8 OCD. Pressure of the liquid B. 65.4 OC C. 62.5 OC D. 57.7 OC3. Which of the following temperatures corresponds to zero on the Kelvin scale ? A. 273 OC B. 0 OC C. -273 OC D. 100 OC 4-3
4. 4. Physics Module Form 4 Chapter 4 - Heat GCKL 2011 4.24 UNDERSTANDING SPECIFIC HEAT CAPACITYDefinition of Heat Capacity 1. Quantity of ______ energy required to raise the temperature of an object by 10C. 2. The unit of heat capacity is ______ 3. Beaker A has (greater, same, less) heat capacity than beaker B. B A A A 4. This means that the (bigger, smaller) the mass, the (larger, smaller) the amount of heat stored. Definition of Specific Heat 1. Quantity of ______ energy required to raise the temperature of ______of a Capacity substance by 10C. 2. The unit of specific heat capacity is ______ 3. An object with low specific heat capacity can be heated up______, as it requires less heat to increase its temperature by 10C. It can be cooled ______due to little amount of heat stored in it. 4. An object with high specific heat capacity takes ______ time to heat up, as it requires more heat to increase its temperature by 10C. It is ______ to cool down due to larger amount of heat stored in it. Q = Pt Pt = mc Q = Heat supplied P = Power of heater T = Time in seconds M = mass of substance C = Specific heat capacity  = Increase in temperature 4-4
5. 5. Physics Module Form 4 Chapter 4 - Heat GCKL 2011Determining the heat capacity of aluminium block 1. The purpose of wrapping the aluminium blok with wool ______ ______to or ______ of heat from the surrounding. 2. Oil in the holes for housing thermometer and the immersion heater is to improve the ______ of heat from the heater to the thermometer through the aluminium block. 3. The immersion heater of 50 W rated power is used for 5 minutes to heat up the aluminium block. If the mass of the alumimium block is 1.0 kg and the rise in temperature is 160C, what is the specific heat capacity of aluminium ? Pt 15000 C   937.5 Jkg-10C-1 m 1 16 4. Specific heat capacity calculated is usually ______ than the standard value because some ______is lost to the surroundings. Aim To investigate the relationship between temperature rise and mass of water Experiment 800C 600C 800C 400C Hypothesis When the mass of water …______ … the temperature rise will …______ …. Manipulated variable ______ of water Responding variable ______ in temperature Fixed variable ______ duration, water, weighing scale, ______ rating of heater used Apparatus Thermometer, water, beaker water, weighing scale Setup 4-5
6. 6. Physics Module Form 4 Chapter 4 - Heat GCKL 2011 Procedure 1. 100 ml of water is placed in a 500 ml beaker. 2. A heater is placed in the water. 3. Heating process is carried out for 1minute. 4. Highest temperature achieved is recorded. 5. Step 2 to 4 is repeated for 200ml, 300ml, 400ml and 500ml of water. Analysis Volume of Final Initial Rise in 1/ (0C-1) water used, temperature, temperature, temperature, V (ml) T2 (0C) T1 (0C)  = T2 – T1 (0C) 100 200 300 400 500 V Conclusion 1/ Applications of specific heat capacityWater as heating agent in heating radiator 4-6
7. 7. Physics Module Form 4 Chapter 4 - Heat GCKL 2011 2. Heat from hot water is released to the cooler surroundings of a room to achieve _____ _____ 3. Cold water will be recirculated to repeat the process continously 1. Cool water is pumped into the hot water reservoir to absorb a large amount of heat due to its ______specific heat capacity. 4. Hot water is cooled by the air from the Water as a coolant in car cooling fins and the fan 2. ______ specific heat engine capacity of water allows it to absorb a large amount of ______from the engine 3. Cool water is recirculated through the engine blocks 1. Cool water is pumped and the process continues into the hot engine while the engine is running 3. Cool air 2. Hot air rises up blows from from the land the sea to replace the space left by 1. During the day the hot air Sea Breeze land gets hotter and than the sea ______ because c land c sea currents in (wind from the sea) the air are formed 3. Cooler air blows from the 2. hot air rises land to from the sea replace the space leftLand Breeze (wind from the by the hot 1. During the land) air and night, the sea convection is hotter than currents in the land the air are because formed. c land c sea 4-7
8. 8. Physics Module Form 4 Chapter 4 - Heat GCKL 2011 Plastic handle _____specific heat capacity Household apparatus and utensils Steel ______specific heat capacity 3. Diagram below shows a bullet moving at a velocity of 60 ms-1 is embedded in a woodenCheck Yourself 1 block. 1. Table below shows four types of liquid with their respective specific heat capacities and boiling points. All the liquids have the same mass and same temperatures of 30oC. If the same amount of heat is supplied to them, which liquid, A, B, C or D will boil first ? Assuming all the energy lost by the bullet is Liquid Specific heat Boiling point converted to heat energy and is absorbed by capacity (Jkg-10C-1) (oC) the bullet. What is the rise in temperature of the bullet ? ( Specific heat capacity of the A 3.0 50 bullet = 120 Jkg-10C-1) B 5.0 80 A. 0.5 oC C 4.2 100 B. 2.0 oC C. 30.0 oC D 0.2 200 D. 60.0 oC 2. Table below shows the specific heat capacity 4. Diagram below shows 200 g of water at 0 oC is of four different metals. poured into a cup containing 400 g of water at 80 oC . Assuming there is no heat loss to the surroundings. Which of the following is the most suitable metal to be used in a rice cooker for fast What is the final temperature of the mixture ? heating ? [ Specific heat capacity of water = 4200 Jkg-10C-1] A. P A. 53 oC B. Q B. 60 oC C. R C. 66 oC D. S D. 70 oC 4-8
9. 9. Physics Module Form 4 Chapter 4 - Heat GCKL 20115. Diagram below shows the temperature-time graph of two solids X and Y of equal mass but of different substances are heated simultaneously by identical heaters. Which of the following comparison is correct? A. Cx > Cy B. Cx < Cy C. Cx = Cy 4-9
10. 10. Physics Module Form 4 Chapter 4 - Heat GCKL 2011 4.34 UNDERSTANDING SPECIFIC LATENT HEAT Definition of 1. Latent Heat is the total energy ________ or released when a substance changes Latent Heat its ________ state completely at a ________ temperature. 2. Latent Heat of fusion is heat absorbed when ________ changes into ________ or heat released when liquid changes into solid at constant________. 3. Latent Heat of vaporization is heat absorbed when ________ changes into ________or heat released when vapour changes into liquid at constant________. 4. Unit for latent heat is ________ . 5. Process in which solid directly changes into vapour is called ________ . 1. Specific Latent Heat of fusion is heat absorbed when 1 kg ________changes into ________or heat released when liquid changes into solid at constant________ . Definition ofSpecific Latent 2. Specific Latent Heat of vaporization is heat absorbed when 1 kg ________ Heat changes into ________or heat released when vapour changes into liquid at constant________ . 3. Unit for latent heat is________. 4. When temperature remain constant, ________energy of the molecules remain constant. However energy absorbed is used to overcome ________ of attraction and atmospheric pressure. 4-10
11. 11. Physics Module Form 4 Chapter 4 - Heat GCKL 2011Heating curve Fill the empty boxes for the heating curve below with the following words Solid, liquid, gas, boiling point, melting point, latent heat of fusion, latent heat of vaporizationCalculation ofspecific latentheat of fusion Mass of water collected in Set A = 49.2 g Mass of water collected in Set B = 6.4 g Power of heater = 80 W Time interval of switching on the heater = 3 minutes 1. Calculate energy supplied by the heater. 2. What is the mass of ice melted due to the heat absorbed from the surroundings? 3. Determine the specific latent heat of fusion of ice. Pt (80)(3  60) 14400 L= = = = m (49.2  6.4) 10 3 42.8 103 4-11
12. 12. Physics Module Form 4 Chapter 4 - Heat GCKL 2011Check Yourself 1 1. Diagram below shows the cooling curve of a power of 1 kW. The beaker and its content is Gas. Temperatures T1 and T2 represents resting on an electronic balance which measures the mass of the beaker and its content. T1 T2 A. Solidification Room temperature B. Boiling Point Solidification point When the water is boiling, it is found that 80 g C. Melting Point Freezing Point of water is boiled away in 3 minutes. D. Melting Point Room temperature What is the specific latent heat of vaporization of water ? 2. Diagram below shows the heating curve of a solid Y of mass 2 kg which is heated by a A. 2.10 x 106 Jkg-1 heater of 70 W power. Which statement B. 2.15 x 106 Jkg-1 below is NOT true ? C. 2.20 x 106 Jkg-1 D. 2.25 x 106 Jkg-1 4. Diagram below shows the arrangement of apparatus used to determine the specific latent heat of fusion of ice. There are two identical sets. One of the sets is called a control set which is without a power supply. A. Specific latent heat of Y is 10500 Jkg-1. B. Specific heat capacity of solid Y and liquid Y are the same C. Total heat used is 1120 J D. Melting point of Y is 10 oC The aim of the control set is 3. Diagram below shows the arrangement of apparatus used to determine the specific latent heat of vaporization of water. The water in the beaker is heated by an immersion heater with a 4-12
13. 13. Physics Module Form 4 Chapter 4 - Heat GCKL 2011 A. To find the mass of ice melted due to the C. To detect any changes in the melting point heat absorbed from the surroundings of the ice B. To find the mass of water formed by D. To find the mass of water evaporated condensation from the vapour in the air5. Heat produced in an engine block of car needs to be transferred out promptly to prevent overheating. This is done by circulating a suitable cooling liquid through the engine block. (a) What is meant by ‘specific heat capacity of water is 4200 Jkg-1oC-1 ? ________________________________________________________________________________ (b) Based on the table above, (i) Explain the suitable characteristics of the cooling liquid to extract heat out of an engine block. High Specific Heat Capacity High specific latent heat of vaporization High boiling point Low rusting rate (ii) Decide which liquid is the most suitable and give reasons for your choice. _____________________________________________________________________________ (c) Total energy released by an engine in 1 hour = 9.0 x 107 J Energy breakdown : mechanical 40% and heat 60% Mass of cooling liquid circulating in 1 hour = 150 kg Temperature of water entering the engine = 30oC Temperature of water exiting the engine = 60oC Based on the information above, (i) Calculate the power of the engine (ii) Calculate the amount of heat produced by the engine in one hour. (iii) Calculate the specific heat capacity of the cooling liquid. 4-13
14. 14. Physics Module Form 4 Chapter 4 - Heat GCKL 2011 (d) Suggest two ways to dissipate the heat from the cooling liquid. 1. ______________________________________________________________________________ 2. ______________________________________________________________________________ 4-14
15. 15. Physics Module Form 4 Chapter 4 - Heat GCKL 2011 4.44 UNDERSTANDING GAS LAWS What is The kinetic theory of gases describes a gas as a large number of small particles (atoms or molecules),kinetic theory all of which are in constant, _______ _______. The rapidly moving particles constantly collide with of gases ? each other and with the walls of the container. Kinetic theory explains ___________ properties of gases, such as pressure, temperature, or volume, by considering their molecular composition and motion. The ___________ of an ideal __________ ____ is a measure of the average _______ _______ of its atoms. Boyles’ Law Charles’ Law Pressure LawDefine the Formulathree gaslaws. Condition T = ___________and P = ______ and V = ______ and _______ of gas are _____ of gas are constant ____ of gas are constant constant (temperature must be in (temperature must be in ______scale) ______ scale) Graphs 4-15
16. 16. Physics Module Form 4 Chapter 4 - Heat GCKL 2011 Experiment al set upCalculation Diagram on the right shows an arrangement to investigate theinvolving relationship between pressure and volume of a fixed mass of gasBoyle’s Law. at constant temperature. The pressure of the air in the glass tube is measured by a pressure gauge and the pressure can be increased by using the bicycle pump. The pump of the gas is 1.5 x 105 Pa when the volume is 80 cm3. (a) Explain how a gas exerts a pressure on the walls of its container. __________________________________________________________________________ __________________________________________________________________________ (b) State the Boyle’s law. __________________________________________________________________________ __________________________________________________________________________ (c) Find the volume of the gas when pressure is 2.5 x 105 Pa (d) Find the pressure of the gas when the volume of the gas is 60 cm3. (e) A bubble of air rises from the bottom of a pond to the surface. As the bubble reaches the surface, its volume is double its original volume. Assume the temperature is constant, find the depth of the pond. [Atmospheric pressure = 10 m of water] 4-16
17. 17. Physics Module Form 4 Chapter 4 - Heat GCKL 2011Question (a) State Charles’ law.involving __________________________________________________________________________Charles’ __________________________________________________________________________Law. (b) Diagrams below shows how (a) the pressure of the gas change with temperature and (b) the volume of the gas change with temperature . (a) (b) (i) Compare the characteristics displayed by the graphs. 1. _______________________________________________________________ 2. _______________________________________________________________ 3. _______________________________________________________________ (ii) Relate the information you have mentioned to form a physics concept. ______________________________________________________________________ ______________________________________________________________________ (iii) Name the concept. ______________________________________________________________________ (c) (i) Define pressure. ______________________________________________________________________ (iv) Using kinetic theory of gas, explain why the pressure of a gas in a fixed container increases with an increase in its temperature. 1. _______________________________________________________________ 2. _______________________________________________________________ 3. _______________________________________________________________ 4-17
18. 18. Physics Module Form 4 Chapter 4 - Heat GCKL 2011Questions Diagram (a) shows the conditon of a snack pack kept in a refrigerator at 18oC, whereas Diagram (b)involving shows the condition of the same snack pack in Borneo Highlands at the same temperature at 18oC.Pressure Law. (a) (b) Based on the above information and observation, (a) State one suitable inference. ______________________________________________________________________ (b) State one suitable hypothesis. ______________________________________________________________________ (c) With the use of appropriate apparatus, describe an experiment framework to test your hypothesis. In your description, state clearly the following: (i) Aim of the experiment ______________________________________________________________________ (ii) Variables used in the experiment _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ (iii) List of apparatus and materials _________ pressure gauge, a _______ with volume scale, rubber tube and retort stand. (iv) Arrangement of the apparatus 4-18
19. 19. Physics Module Form 4 Chapter 4 - Heat GCKL 2011 (v) The procedure of the experiment which include the method of controlling the manipulated variable and the method of measuring the responding variable 1. The apparatus for the experiment is set up as shown in the diagram 2. The ______ of the syringe is pressed down slowly until the volume of air inside the syringe is 100 cm3 3. The ________ of the air in the syringe is read from the Bourdon gauge 4. The experiment is repeated with ________of air fixed at 80 cm3, 5. Make sure that there is no _____ and no increase in ___________ . 6. (vi) The way you would tabulate the data Volume, V (cm3) Pressure, P (Pa) 100.0 (vii) The way you would analyze the data 80.0 60.0 40.0 20.0Check Yourself 1 1. Diagram below shows a valve P connecting A. 2.0 x 10 -4 m3 two cylinders, A dan B. When P is opened, gas from cylinder A moves to cylinder B. B. 4.0 x 10 -4 m3 C. 5.0 x 10 -4 m3 P D. 8.0 x 10 -4 m3 3. Diagram below shows capillary tubes (a) and Which physical quantities does not change ? (b) which are identical. If the atmospheric pressure is 75 cmHg, determine the length of A. Pressure gas column x and the pressure p. B. Volume C. Mass D. Density 2. The graph in the diagram below shows the relationship between pressure, P and volume, V of a fixed mass of gas at constant temperature. Length Pressure What is the value of V2 ? x (cm) p (cmHg) 4-19
20. 20. Physics Module Form 4 Chapter 4 - Heat GCKL 2010 A. 24.0 70 B. 21.0 75 C. 22.4 80 5. Air at a temperature of 27oC is kept in a D. 21.0 70 container at a pressure of 1 atmosphere. What is the pressure of the air, in atmosphere, if it is4. Diagram below shows a fan is allowed to blow heated to a temperature of 77oC ? in a closed room for an hour. What are the A. 0.35 possible changes to the pressure and B. 0.86 temperature of the air in the room ? C. 1.17 D. 2.85 6. Table below shows the volume and temperature of a fixed mass of gas kept at constant pressure. V (cm3) 50 100 T(oC) 27 x Temperature Pressure What is the value of x ? A. Increases no change B. No change increases A. 54 oC C. Decreases increases B. 300 oC D. Increases Increases C. 327 oC D. 600 oC 4-20