AIDA SYAFIQAH SILMI PHYSICS BUDDIES O RI O N ORION BESTSELLER CHAPTER 4: HEAT QUICK REVISION! 100% EFFECTIVE Physics Form 4 KSSM SPM Comprehensive Notes MCQ Questions Answer Sheet Additional Info QR Code Video
CHAPTER 4: HEAT Physics Form 4 KSSM PHYSICS BUDDIES QUICK REVISION! Aida Syafiqah Silmi Head Of ice: ORION PUBLISH SDN. BHD. (89120-H) 66, Jalan Pingai, Taman Pelangi, 80400 Johor Bahru, Johor Darul Takzim, Malaysia. Tel: 07-331 6288 Fax: 07-332 9201 E-mail: www.orionbooks.com Orion Publish Sdn. Bhd. 2023 First Published 2023 All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, photocopying, mechanical, recording or otherwise, without the prior permission of Orion Publish Sdn. Bhd. Printed in Malaysia by The Commercial Press Sdn. Bhd. Lot 8, Jalan P10/10, Kawasan Perusahaan Bangi, Bandar Baru Bangi, 43650, Selangor Darul Ehsan, Malaysia i
All praise to Allah SWT for giving me the courage and strength to complete this lesson book. I would like to express my special thanks of gratitude to my lecturer, Dr. Norezan. It could not have been possible to complete and done the lesson book without her guidance. To all my family, friends, and others who always shared their support either morally, financially, or physically, I would like to thank all of you so much. I hope that my lesson book will benefit science students, especially in the physics stream in gaining a better knowledge of the topics that are included in this book. Author and Editor: Aida Syafiqah binti Silmi First Published 2023 Published for: School of Science (SCE551) Publisher: Orion Publish Sdn. Bhd. Layout and Design: Canva.com ACKNOWLEDGEMENT ii
Highlights important facts and keywords Uses student-friendly layout to make learning exciting and stimulating Incorporates contextual learning through HOTS and i-THINK Based on the 2023 SPM format PREFACE SPECIAL FEATURES OF PHYSICS BUDDIES This book is written by authors who have extensive experience in teaching, writing, and assessing examination papers. PHYSICS BUDDIES is published to help students with final revisions leading to the Sijil Pelajaran Malaysia (SPM) examination. The book is specially planned based on the Dokumen Standard Kurikulum dan Pentaksiran (DSKP) Form 4 and Form 5, textbooks, reference books, guidebooks, and SPM Assessment Format provided by the Lembaga Peperiksaan. iii
4.1 Thermal Equilibrium 4.2 Specific Heat Capacity 4.3 Specific Latent Heat 4.4 Gas Laws Summative Practice Answer Sheet Glossary References 1 - 3 3 - 4 5 - 6 7 - 10 11 12 12 12 CONTENTS COPYRIGHT PAGE ACKNOWLEDGEMENT PREFACE i ii iii CHAPTER 4: HEAT Theme 3: Heat
CHAPTER 4 HEAT How can the metal spoon cool down the hot coffee? What is the final condition of the spoon and the coffee? Learning Outcome Explain thermal equilibrium in daily life Calibrate a liquid-in-glass thermometer using two fixed point. At the end of this subtopic, students should be able to: 1. 2. When a cold metal spoon is dipped into a cup of hot coffee, the spoon and the coffee are said to be in thermal contact because heat energy can be transferred between two bodies When two objects are in thermal contact, the temperature of the hot object will drop while the temperature of the cold object will rise until the temperature of both objects become the same. Net heat transfer between the two objects becomes zero. Both objects are said to be in thermal equilibrium. Hot object, P is in thermal contact with cold object, Q. The rate of heat transfer from P to Q is higher than the rate of heat transfer from Q to P. Photograph 4.1 A cold metal spoon in a cup of hot coffee 4.1 Thermal Equilibrium 1 PHYSICS BUDDIES Chapter 4 Heat 4.1 Thermal Equilibrium
Heating object Cooling object Hot air in oven is in thermal contact with cake batter. Heat from the hot air flows to the cake batter. This causes the cake batter to be beated until it is baked. Heat from the patient's body flows to the thermometer until the temperature of the patient and the thermometer become the same. The body temperature of the patient can be determined because thermal equilibrium occurs. When food is kept in the refrigerator, heat from the food flows to the air in the refrigerator until thermal equilibrium occurs. Temperature of the food drops and the food stays fresh for a longer period. Drinks are cooled by adding several ice cubes. Ice cubes abserb heat from the drink and melt. Melted lee cubes absorb heat from the drink until thermal equilibrium is achieved. Temperature of P and temperature of O become the same. The rate of heat transfer from Pto Q is the same as the rate of heat transfer from Q to P. Net heat transfer between P and Q becomes zero. P and Q are in a state of thermal equilibrium. To Calibrate a Liquid-in-glass Thermometer Using Two Fixed Points When two fixed points (100°C and 0°C) have been marked, the range in between is then divided equally into 100 division. The thermometer is now calibrated and can be used to measure temperature. There is a net transfer of heat from P to Q. Therefore, temperature of P drops and temperature of Q rises. Thermal Equilibrium in Daily Life Figure 4.1 Flow of heat energy and thermal equilibrium 2 PHYSICS BUDDIES Chapter 4 Heat
Figure 4.2 shows the calibration of temperature scale between upper fixed point (100°C) and lower fixed point (0°C). Heat capacity, C of an object is the quantity of heat needed to raise the temperature of the object by 1°C. C = Q that Q = quantity of heat supplied Δθ Δθ = change in temperature Unit for C = J °C Specific heat capacity, c of a substance is the quantity of heat needed to raise the temperature of 1 kg mass of the substance by 1°C. c = Q that Q = quantity of heat supplied (J) mΔθ Δθ = change in temperature (°C or K) m = mass (kg) Unit for c = J °C Learning Outcome Explain heat capacity, C Define specific heat capacity of substance Analyze applications of specific heat capacity At the end of this subtopic, students should be able to: 1. 2. 3. Learning Outcome Heat capacity, C C = Q Δθ c = Q mΔθ 4.2 Specific Heat Capacity -1 -1 Heat capacity Specific Heat Capacity of Substance Figure 4.3 Different materials have different specific heat capacities Table 4.1 Specific heat capacity of different substances Fo rmula Reminde r Specific heat capacity, c Figure 4.2 Calibrating a thermometer 3 https://youtu.be/Q4-Je50CVNs Calibrating a thermometer process: PHYSICS BUDDIES Chapter 4 Heat
Cook ing ut ensil Car radiator syst em Sea br e eze Land br e eze E x a m p l e PHYSICS BUDDIES Chapter 4 Heat Woks are made of metal with low specific heat capacity. As such, food can be fried at high temperature in a short time. Clay pots on the other hand are made of clay which has a high specific heat capacity. As such, food can stay hot for a long time. Metal wok Clay pot Burning of fuel in car engines produces large amounts of heat. This heat needs to be released to avoid overheating the engine. Water has a high specific heat capacity and is used as a cooling agent. A pump will pump water into the engine block. Water will flow through the engine block to absorb heat produced. Hot water flows to the radiator. Cold air is sucked in by fans so that heat in the hot water can be released quickly through cooling fins. Land has a lower specific heat capacity than the sea Therefore, temperature on land rises more quickly than temperature in the sea during daytime. The air on land becomes hot and rises upwards. Cold air from the sea moves towards land as sea breeze. Sea has a higher specific heat capacity than land. So, temperature in the sea drops more slowly than temperature on land at night. Hot air above the sea rises upwards. Cold air above the land moves towards the sea as land breeze. Applications of Specific Heat Capacity A 100 g of water at 30°C is poured into a beaker containing 200 g of water at 70°C. What is the final temperature, T of the mixture? Solution QAbsorbed = QReleased mcθ = mcθ 100c(T - 30) = 200c(70 - T) 100T - 3000 = 14 000 - 200T 300T = 17 000 T = 56.67°C 4 Car radiation system: https://youtu.be/V7inC4lOpGs
Learning Outcome What is latent heat? What happen in change of phase? Specific latent heat, l of a substance is the quantity of heat, Q that is absorbed or released during a change of phase of 1 kg of the substance without any change in its temperature. l = Q that Q = latent heat absorbed or released by the substances m m = mass of the substance (kg) Unit for l = J kg 4.3 Specific Latent Heat Explain latent heat Define specific latent heat, specific latent heat of fusion and specific latent heat of vaporization Analyze applications of specific heat capacity At the end of this subtopic, students should be able to: 1. 2. 3. Learning Outcome Figure 4.4 above shows the changes in phase of matter. During the changes in the phase of matter such as melting and boiling, the temperature remains constant eve though heat is being supplied continually. Heat that is absorbed during melting and boiling without change in temperature is known as latent heat. During condensation and freezing, latent heat is released without temperature change. Figure 4.4 Changes in phases of matter Latent Heat -1 Specific latent heat of fusion, l, of a substance is the quantity of heat, Q that is absorbed during melting or the quantity of heat released during freezing of 1 kg of the substance without any change in temperature. Specific latent heat of vaporization, l of a substance is the quantity of heat, Q that is absorbed during boiling or the quantity of heat released during condensation of 1 kg of the substance without any change in temperature. 5 Specific latent heat: https://youtu.be/8 VmkdzRE8sQ PHYSICS BUDDIES Chapter 4 Heat
Heat absorbed Temperature is constant Heat absorbed Temperature is constant Melting iced is used to preserve food due to its ability to absorb large amount of latent heat Figure 4.5 The heating curve Figure 4.6 The cooling curve Applications of Specific Latent Heat Photograph 4.2 Preserving food using ice cubes Photograph 4.3 Steam cooking Latent heat is released to food when steam condenses into water E x a m p l e An ice cube of 180 g is fully turned into water in 5 minutes. If the power of the heater used is 200 W, calculate the specific latent heat of fusion of the ice cube. Solution QAbsorbed = QReleased ml = pt 0.18t = 200(300) l = 333333.33 J kg-1 6 PHYSICS BUDDIES Chapter 4 Heat
Characteristic of gas Description Pressure Gas molecules always move randomly. When gas molecules collide with the wall of the container and rebound, a force is exerted on the wall of the container. Force per unit area is the pressure of the gas. Temperature Temparature Average kinetic energy of gas molecules increases with temperature. Volume Gas molecules move freely and fill the entire space of the container. Volume of gas is the same as the volume of its container. Learning Outcome Explain characteristic of gas Differentiate the relationship between pressure, temperature, and volume of gas At the end of this subtopic, students should be able to: 1. 2. Learning Outcome How does the pressure, temperature and volume of gas relate to each other? 4.4 Gas Law Table 4.2 Pressure, temperature and volume of gas based on the Kinetic Theory of Gas Pressure, Temperature, and Volume of Gas Graph 4.1 P against V Graph 4.2 P against 1 V 7 PHYSICS BUDDIES Chapter 4 Heat
The graph of P against V shows that pressure decreases with volume. Graph of P against 1/V however shows a straight line passing through the origin. This shows that pressure is inversely proportional to volume. Useful Tips PVT triangle For Boyle's Law, temperature is constant PV = constant P1VI = P2V2 Figure 4.5 Fixed mass of a gas compressed at a constant temperature When the volume of gas decreases, the same number of molecules move in a smaller space. Therefore, the number of molecules per unit volume increases. This causes the rate of collisions between molecules and the walls of the container to increase. Force per unit area on the wall of the container also increases. As such, gas pressure increases. The graph of V against T for gas shows a straight line passing through the origin. This shows that the volume of gas is directly proportional to absolute temperature. Boyle's Law Boyle's Law states that pressure is inversely proportional to volume for a fixed mass of gas at constant temperature. P ∝ 1/V P = k(1/V) that k is constant P = gas pressure (Pa) V = gas volume (m ) As such, PV= k If a gas experiences a charge in pressure and volume from condition 1 to condition 2, PV = k, condition 1 of gas, P1V1 = k condition 2 of gas, P2V2 = k therefore, P1V1 = P2V2 3 Relationship between Volume and Temperature of Gas Graph 4.3 V against T for a gas 8 PHYSICS BUDDIES Chapter 4 Heat
When the temperature of the gas increases, the average kinetic energy of its molecules increases, and the molecules move with higher velocity. To keep a constant gas pressure, the volume of gas increases so that the rate of collision of gas molecules with the walls of the container is unchanged. The graph of P against T of gas is a straight line through the origin. This shows that gas pressure is directly proportional to absolute temperature. Charles' Law states that volume is directly proportional to absolute temperature for a fixed mass of gas at constant pressure. V ∝ T V = kT that k is constant T = absolute temperature (K) V = gas volume (m ) As such, V/T = k If a gas experiences a change in volume and temperature from condition 1 to condition 2, V/T = k, condition 1 of gas, V1/T1 = k condition 2 of gas, V2/T2 = k therefore, V1/T1 = V2/T2 3 Useful Tips For Charles' Law, pressure is constant V/T = constant V1/T1 = V2T2 Figure 4.6 Fixed mass of a gas heated at a constant temperature Charles' Law Relationship between Pressure and Temperature of Gas Graph 4.4 P against T 9 Additional Info Joseph Louis Gay-Lussac (1778-1850) is a French physicist and chemist who made quantitative investigation about the characteristics of gas. He also investigated the magnetic field of the Earth and composition of the atmosphere at high altitudes. In addition, he found two new elements, boron and iodine. PHYSICS BUDDIES Chapter 4 Heat
Gay-Lussac's Law Gay-Lussac's Law states that pressure is directly proportional to absolute temperature of a fixed mass of gas at constant volume. P ∝ T P = kT that k is constant P = pressure (Pa) T = absolute temperature (K) As such, P/T = k If a gas experiences a change in pressure and temperature from condition 1 to condition 2, P/T = k, condition 1 of gas, P1/T1 = k condition 2 of gas, P2/T2 = k therefore, P1/T1 = P2/T2 3 Useful Tips For Gay-Lussac's Law, volume is constant P/T = constant P1/T1 = P2T2 When the temperature of the gas increases, average kinetic energy of its molecules increases, and the molecules move with higher velocity. As the volume of gas does not change. the rate of collision of gas molecules with the walls of the container increases. Force per unit area on the wall of the container also increases. As such, gas pressure increases. Figure 4.7 Fixed mass of a gas heated at a constant volume E x a m p l e The air pressure in a car tyre is 210 kPa at a temperature of 27°C. What is the temperature of the air in the tyre at a pressure of 220 kPa? [Assume that the volume of the air in the tyre is constant] Solution P1T1 = P2T2 210/300 = 220/T T = 314.3 K = 41.3°C 10 PHYSICS BUDDIES Chapter 4 Heat
X Y Summative Practice 1. Diagram 1 shows two aluminum blocks, X and Y, are in contact. The initial temperatures of X and Y are 120°C and 10°C respectively. Which statement is not correct when X and Y are at thermal equilibrium? A. The temperature of X is equal to the temperature of Y. B. The quantity of heat in X is the same as in Y. C. The net rate of heat flow between X and Y is zero. 2. Ali and his team members who took part in a hiking expedition found that water boils faster when heated at high regions compared to heating at low regions, even though the same rate of energy was supplied. Which of the following statements is the correct explanation for the situation they observed? A. The temperature is lower at high regions. B. The air is less dense at high regions. С. The rate of heat lost is slower al high regions. D. The atmospheric pressure is lower at high regions. Multiple Choice Question Diagram 1 3. Which phenomenon shows the application of latent heat of vaporization in everyday life? A. Steaming fish B. Cooling a car engine С. Preserving food with melting ice D. Reading temperature from a mercury-inglass thermometer 4. Diagram 2 shows a phenomenon. The land heats up faster than the sea causing the cooler air from the sea move towards the land as sea breeze. It is caused by the sea and the land having different A. latent heat of fusion. B. specific heat capacity. C. boiling point. D. density. 5. An air bubble which has a volume of 5 cm} was released at a depth of 100 m. What is the volume of the air bubble at a depth of 45 m? [Atmospheric pressure = 10 m of water] A. 2.25 cm3 B. 2.50 cm3 С. 7.25 cm3 D. 10.00 cm3 Diagram 2 11 PHYSICS BUDDIES Chapter 4 Heat
Answers B D A B 1. 2. 3. 4. 5. D Glossary Boiling point of water Constant temperature at which water changes into steam Gas laws Laws that relate absolute temperature, pressure and volume of a fixed mass of gas Linear Linear magnification Ratio of image height to object height Melting point of ice Constant temperature at which ice changes into water Temperature Degree of hotness of a substance Vacuum Space entirely devoid of matter References Hean, B. O., Md Mustafa, K. A., & Ragavan, R.,C. C. Song & C. K. Kheng (2019). Chapter 4 Heat, Physics Form 4 (pp. 118-148). Chong Chee Sian. (2022). Ranger SPM 2022 (Physics) (Vol. 9789672806868). Penerbitan Pelangi Sdn. Bhd. 12 PHYSICS BUDDIES Chapter 4 Heat
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