Lesson 9

HEAT & TEMPERATURE

Temperature• It is the measure of average kinetic energy

of the particles in a body.Kinetic Molecular Theory of Matter

“All particles of matter are in constant motion.”

• Temperature is fundamental quantity of any matter.

• Units such as Fahrenheit, Celsius/ Centigrade and Kelvin are used to quantify temperature.

Thermometer• It is a device used to measure

temperature.

Fahrenheit• It was formulated by

Daniel Fahrenheit based on his experiment using a mercuric thermometer and ice-salt solution.

Celsius• It was invented by

Anders Celsius using pure water.

Kelvin• William Thomson,

also known as Lord Kelvin devised the absolute zero temperature scale.

K = 273.15 °C

Internal Energy• It may seem that the glass-water

system has zero energy. But in the microscopic level, the molecules are in constant motion(kinetic energy) and attractive forces between molecules(potential energy).

• The combination of motion an attractive energy of the molecules gives the internal energy of an object.

Which has the highest internal energy?

90°C 90°C

Which has the highest internal energy?

90°C 90°C

Which has the highest internal energy?

90°C 100°C

Which has the highest internal energy?

100°C

90°C

Which has the highest internal energy?

100°C

50°C

Thermal Equilibrium• It is a condition when

bodies in a system cease to transfer heat and is manifested by a single temperature.

Heat• It is a form of energy not

inherent in a body. Its presence depends on the difference in temperatures of two bodies in contact.

• The transfer of heat is a natural process and will only stop if both bodies possess the same temperature.

A

B

Heat• It is a form of energy not

inherent in a body. Its presence depends on the difference in temperatures of two bodies in contact.

• The transfer of heat is a natural process and will only stop if both bodies possess the same temperature.

A

B