## Note on Heat and temperature

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#### 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.

• 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.
.

### Very Short Questions

 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.

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

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kilogram

Joule

meter

degree

Odometer

Thermometer

Speedometer

Barometer

• ### The hotness on an object is determined by its ______.

pressure

heat

temperature

none of these

• ### The temperature of boiling water cannot be measured by ______.

clinical thermometer

All the answers are correct

laboratory thermometer

both clinical and laboratory thermometer

• ### A wooden spoon is dipped in a cup of ice cream , its other end ______.

becomes hot

does not become cold

becomes cold by the process of radiation

becomes cold

39 °C

100°C

357°C

0°C

• ### Higher the temperature of the body ______ the kinetic energy of the molecules of that body.

Higher

none of these

Lower

Same

• ### What happens to the object when heat energy is supplied to it?

all the answers are correct
the molecules gets far apart from each other
the object gets hot
the molecules of the object moves faster
• ### The device that measures the degree of hotness and coldness of a body is called ______.

calorimeter

temperaturemeter

thermometer

lactometer

water

mercury

alcohol

ethanol

• ### Process of division of temperature scale in thermometer is called ______.

separation of scale in thermometer

calibration of thermometer

division of thermometer

marking of thermometer

• ### The advantages of using mercury in a thermometer is ______.

it does not stick in the glass

all of the answers are right

the calibration of mercury is easier as it expands uniformly at ordinary temperature

it can be used to measure wide range of temperature

• ### Clinical thermometer was invented by ______.

Sir Isaac Newton

Sir Clifford Allbutt

Sir Arthur King

Graham Bell

1890 A.D.

1850 A.D.

1860 A.D.

1870 A.D.

• ### The thermometer used to measure the maximum and minimum temperature of a day is called ______.

horse shoe thermometer

clinical thermometer

day and night thermometer

maximum and minimum thermometer

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