## Heat and temperature

Subject: Science

#### Overview

We use the expressions of hot and cold in our daily life on a number of occasions. Heat is the sum of kinetic energy of all molecules of a substance whereas the degree of hotness and coldness of an object is called its temperature. This note presents information about heat and temperature.

#### Heat

Heat is the sum of kinetic energy of all molecules of a substance. We use the expressions of hot and cold in our daily life on a number of occasions. We use heat for cooking food and keeping our body warm. We can get heat from coal, gas or electricity and sun. The degree of hotness and coldness of an object is called its temperature. Temperature is usually measured in the Celsius scale or Fahrenheit. The normal human body temperature is 98.40 Fahrenheit or 36.90 Celsius.

#### Temperature

Temperature is a measure of how hot or cold a body is. Temperature is usually measured in the Celsius scale or Fahrenheit scale. Temperature of the system can be defined as the property that determines whether or not the body is in thermal equilibrium with the neighbouring system. If the number of systems is in thermal equilibrium, this common property of the system can be represented by the simple numeric value called temperature.

Differences between Heat and Temperature

The differences between heat and temperature can be summarised in points as follows:

 S.N Heat S.N Temperature 1. Heat is the form of energy that flows from the system to its surroundings. 1. Temperature is the result of heat. 2. Mass of the body affects the total heat. 2. Mass of body does not effect on temperature but depends on the molecular vibration of the body. 3. Heat is measured in joules or calories. 4.2 Joules = 1 calorie 3. Temperature is measured in degree Celsius or degree Fahrenheit or Kelvin Scale. 4. Heat is measured by using a Calorimeter. 4. Temperature is measured using the thermometer.
##### Things to remember
• Heat is the sum of kinetic energy of all molecules of a substance.
• We use heat for cooking food and keeping our body warm.
• We can get heat from coal, gas or electricity and sun.
• The degree of hotness and coldness of an object is called its temperature.
• It includes every relationship which established among the people.
• There can be more than one community in a society. Community smaller than society.
• It is a network of social relationships which cannot see or touched.
• common interests and common objectives are not necessary for society.
##### The Heating Song
 S.No. Heat Temperature 1 Heat is a kinetic energy of all molecules of a substance. Temperature is the degree of hotness and coldness of a body. 2 Its SI unit is joule. Its SI unit is Kelvin.

The two common scales of the temperature are the Celsius scale and the Fahrenheit scale.

The temperature of pure melting ice and that of steam on the Celsius scale is 0 degree centigrade to 100 degree centigrade.

\begin{align*}\frac {(K-273)}{100}= \frac {(C-0)}{100} \\ \text {or,}\: (100 – 273) &= C \\ \text {or,}\: C &= -273 + 100 \\ \text {or,}\: C &= -173 \\ \text {Thus,}\: 100\:K &= -173^o\:C. \\ \end{align*}

\begin{align*} \frac {(C – 0)}{ 100} &= \frac {(K- 273)}{100} \\ \text {or,}\: 220 &= K-273 \\\text {or,}\: K &= 273 + 220 \\ K &= 493 \\ \text {Thus} \: 220^o\:C &= 493\: K \\ \end{align*}

\begin{align*}\frac {(C-0)}{100} &= \frac {(F-32)}{ 180} \\\text {or,}\: \frac {30}{10} &= \frac {(F-32)}{18} \\\text {or,}\: 30 \times 18 &= (F – 32) \times 10 \\ \text {or,}\: 540 &= 10F – 320 \\ \text {or,}\: 540 + 320 &= 10F \\ \text {or,} F = \frac {860}{10} \\ \text {Thus}\: 30^o\:C &= 86^o\:F \\ \end{align*}

One calorie is the amount of the heat required to raise the temperature of one gram of water by 1°C.

$$\frac {(C – 0)}{100} = \frac {(F – 32)} {180} = \frac {(K – 273)} {100}$$