Introheat

Introduction

If the development of computers and internet by physicists have changed our lives since the last century, another equally significant contribution by physicists had been the invention of engines in the eighteenth century. Engines convert the chemical energy of fuel to movement or kinetic energy (to sound sophisticated) by heating and burning the fuel.

Heat, like light and sound is a form of energy. Although our ancients had been using heat energy over millenia, this concept along with its theories and applications like several other concepts in physics had its roots as recent as the nineteenth century. Rubbing ones hands together to feel warm by transferring the 'caloric' didn't seem odd?

The popular unit of heat energy 'calorie' is now replaced by "JOULE" (named after James P. Joule) in the SI system. Calorie is the amount of heat energy that is needed to raise the temperature of 1 g of water by 1 ⁰C from 14.5 ⁰C to 15.5 ⁰C at normal atmospheric pressure.

Most of us are familiar with the unit calorie that is still widely used by dieticians. Food stuffs is the departmental stores have details of energy among other useful information. However you must recognize that since the amount of heat energy spent by us when we burn food is large, energy is better given in terms of kilocalories (kcal) rather than calories (cal). A dieticians cal is actually a physicists kcal.

1 calorie = 4.186 joules

QUESTIONS on Photograph 1

1. The concept that can also be called 'heat inertia' is _______________
2. The apparatus you can see in this photograph are used to determine the specific heat capacity of the metal ____________
3. _______________ is the amount of heat energy that is required to raise the temperature of 1 kg of a substance through a temperature of 1 *C
4. In order to heat water in the ____________, we must have a bunsen burner, ____________, _____________, _______________, _____________ and a supply of gas as illustrated.
5. The copper block is placed on a ______________ cup placed upside down.
6. Styrofoam is used because it is a good ________________
7. A definite amount of water can be poured into this cup by using a _________________ seen on the left of this photograph.
8. To record the temperature precisely we have two digital _____________ that can be seen on the right of the photograph. These two ______________ can be held in place by the two _____________ seen at the back of this photograph.
9. Using the paper towels shown in the front the metal cube can be __________ after heating the block inside boiling water before quickly transferring it to the _______________ cup containing a measured amount of cold water.
10. The principle used to determine the specific heat capacity is called the ______________________. According to this principle if heat losses to the surroundings are neglected, the heat ___________ by a hot body = the heat __________ by the cold body. This follows from the law of conservation of _________

(20 marks)