TEST 7A and 7B.

Review

Our sense of temperature is no always accurate. Thermometers increase the accuracy with which temperature is measured or gauged.

As the temperature of a substance changes, its physical characteristics may change as well. These changes can be used to measure temperature.

Water boil at 100ªC. It freezes at 0ºC. These temperatures form the basis for the Celsius temperature scale. Highest Temperature on earth ever: 58 ºC (Libya North Africa). Lowest temperature on earth: -88 (Vostok station, Antartica). Surface of the sun: 6000. Center of the Earth: 2000-5000. Atomic explosion. 300 to 400 millions.

Our bodies have many processes for regulating temperature, all of which involve the production or elimination of heat. ex: fevers, goose bumps, sweating, or shivering.

Most thermometers measure temperature by gauging the expansion of a gas or a liquid. There are many different kinds of thermometers, each designed for use in a specific setting.

A thermometer is an instrument used to measure temperature, and it works by undergoing physical changes. Most materials expand when heated and contract when cooled (except water). The most commonly used type of thermometer is base on such change. When a liquid, such as mercury of alcohol, is sealed in and evacuated glass tube, it can be used as a thermometer.

When a thermometer is heated ,its liquid expands more than the glass, so it rises in the tube. Cooling causes the liquid to contract and fall.

Temperature is the hotness or coldness of a material. Measures the warmth of an object.

Heat: Is the energy of the random motion of the molecules in an object. The more heat a substance contains, the faster its molecules are moving on average).

Hot and cold water mixed in equal volumes result in water with a temperature halfway between the two.

Exercises:

-Two parts of at 10 ºC and one part at 40 ºC are mixed, find the average temperature for the mixture (Equal amount ).

-30 ml at 60ºC mixed with 60 ml at 30 ºC. Find the average temeprature of the mixture.

Heat is a form of energy. The joule is the metric unit used to measure energy. It is approximately equal to the amount of energy required to raise a 100 g mass 1 m.

The human body requires a certain number of calories daily in order to function properly. Teenager normaly require 8000 to 10000 Kj per day. About half of this is used to keep your body's basic system running- your heart beating, your lungs breathing, and your brain thinking. The rest is used for movement. If your eat too little, you won't have enough every. If your eat too much, you will put on mass- about 1 kg for every 35,000 KJ. Practice conversion KJ to Calorie. 1 calorie=4.2 KJ. Exercises. Convert 6000 KJ into calories. 10,000 KJ into calories.

What is specific heat? Amount of heat needed to raise the temperature of 1 g of a substance by 1 ºC. Specific heat of water is 4.2 J/g ºC.

- Exercises. 100 g, 1000 g, and 50 g of water. 800 J, 400 J, 200 J. were added. How much would the temperature raise.