Heat and Temperature PDF

# Heat and Temperature ## 01: History Until the end of the 18th century, scientists thought that the ultimate liquid called caloric. In 1798, an American scientist named Benzamine Thompson Rumford (1753-1814) proved that there is nothing in the reality of the calorie. - **Sir Benjamin Thompson**...

# Heat and Temperature ## 01: History Until the end of the 18th century, scientists thought that the ultimate liquid called caloric. In 1798, an American scientist named Benzamine Thompson Rumford (1753-1814) proved that there is nothing in the reality of the calorie. - **Sir Benjamin Thompson** - Born: March 26, 1753, Woburn, Massachusetts - Died: August 21, 1814 (aged 61), Paris It was about 40 years later that an English physicist, James Prescott (24 December 1818 – 11 October 1889), discovered that heat must be just another form of energy. - **James Prescott Joule** - James Joule - physicist ## 02: What is Heat & Temperature? **Heat:** Heat is a form of energy which flows from higher temperature to lower temperature by conduction, convection and radiation processes. **Example:** The biggest example of heat energy in our solar system is the sun itself. The sun radiates heat to warm up the planet earth. **Temperature:** Temperature is the thermal state of a body which controls the flow of heat from one body to another & determines the direction of heat flow. ## 03: Source of Heat & Temperature - **Natural Source** - **The Sun:** When the sun's energy reaches the earth, 30% of it is immediately reflected back out into space, only 70% remains to interact with the earth and warm it up. - **Artificial Source** - **Chemical Action:** When fuels like coal, kerosene, wood & gasoline are burned they are used as artificial sources of heat ## 04: Type of Scale - **1. Celsius Scale.** - **2. Fahrenheit scale.** - **3. Kelvin Scale.** | Scale | Description | |---|---| | Kelvin scale | 373 K, 310 K, 273 K | | Celsius scale | 100°C, 37.0°C, 0°C | | Fahrenheit scale | 212°F, 98.6°F, 32°F | ## 05: Celsius Scale **Celsius Scale:** Commonly known as Centigrade Scale. This scale was devised in 1741 by a Swedish astronomer, Andres Celsius, based on the properties of water. - **Anders Celsius** - Born: 27 November 1701, Uppsala, Sweden - Died: 25 April 1744 (aged 42), Uppsala, Sweden ## 06: Fahrenheit Scale **Fahrenheit Scale:** The Fahrenheit scale was devised by Daniel Gabriel Fahrenheit, a German physicist. Units states of America and England use the Fahrenheit scale for weather observation & other purposes. ## 07: Kelvin scale **Kelvin Scale:** Named after Sir Willam Thomsom (Lord Kelvin) who deserves it (26 June 1824 – 17 December 1907). ## 08: Absolute Zero & Temperature scale comparisons. - Defined as 0 Kelvin. - Average temperature of space is 2.7k. - Scientists have gotten within a fraction of absolute zero, but it is impossible to ever completely stop the movement of an atom, since that means it has zero energy ## 09: Type of Heat Transfer - 1. Conduction - 2. Convection - 3. Radiation ## 10: Conduction - This process occurs in most solids. - Heat is transferred by direct contact. - Solids are the best conductors of heat. - Transmission of heat from particle to particle. ## 11: Convection - This process occurs in liquids and gasses. - Heat is transferred by the movement of currents. - Is the transport of heat within a substance by the actual movement of the substance itself. ## 12: Radiation - Transfer of heat through electromagnetic waves. - The heated substance is not necessary. ## 13: Relation between Heat and Temperature We can calculate the heat released or absorbed using the specific heat capacity, the mass of the substance, and the change in temperature in the following equation: $q = m \times C \times \Delta T$. ## 14: Difference between heat and temperature | Characteristic | Heat | Temperature | |---|---|---| | Definition | A form of energy in motion | The degree of hotness or coldness of a body | | Cause & Effect | Cause of temperature | Effect of heat | | Direction of Flow | Does not determine the direction of flow | Determines the direction of flow, from higher to lower temperature | | Measurement | Joules or calories | Celsius (°C), Fahrenheit (°F), or Kelvin (K) scale | ## 15: Causes of heat - Sun - Petroleum - Natural gas - Coal - Solar energy ## 16: Causes of Temperature - Sun - Petroleum - Natural gas - Coal - Solar energy ## 17: Results of Heat & Temperature Heat, q, is thermal energy transferred from a hotter system to a cooler system that are in contact. Temperature is a measure of the average kinetic energy of the atoms or molecules in the system. We can calculate the heat released or absorbed using the specific heat capacity C, the mass of the substance m, and the change in temperature ΔT in the equation: $q = m \times C \times \Delta T$.