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C7 heat as a form of energy

by cikgusidah on Oct 13, 2010

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Chapter 7 Heat - Science Form 1

Chapter 7 Heat - Science Form 1

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C7 heat as a form of energyPresentation Transcript

• CHAPTER 7HEAT
7.1 HEAT AS A FORM OF ENERGY
• CHAPTER 7 HEAT
• Heat is a form of ENERGY (can be used to do work)
Heat cause objects to become hot
Example :
We feel hot under the sun
We feel cold when the sun is not not shining
• SOURCES OF HEAT
1. Friction
rubbing two hands together
2. Combustion /burning
burning of candles
Electricity
rice cooker
• Energy from friction creates heat. For example when you rub your hands, sharpen a pencil, make a skid mark with your bike, or use the brakes on your car, friction generates heat
A thermal infrared image of a pencil after being sharpened (left) and of hot brakes in a car (right). Notice the hot tip of the pencil.
FRICTION
• A thermal infrared image of a hair dryer and a flourescent light bulb
ELECTRICITY
• When a substance is burned , heat is also released
Burning firewood
COMBUSTION/BURNING
• USES OF HEAT
IN DAILY LIFE
Cooking
Drying clothes
Keep us warm
Causes breeze (sea breeze & land breeze)
Solar energy
Preserving food
• HEAT
& TEMPERATURE
• Temperature – a measure of the degree of hotness of an object or substance
Unit for temperature
– degree Celsius / 0C
Temperature is not energy, but a measure of it. Heat is energy.
• Figure 1 shows three beakers W, X, and Y containing different amount of water.
Figure 1
Which of the following shows the quantities of heat in ascending order?
A W, X, Y
B Y, X, W
C X, W, Y
D Y, W, X
• Figure 2 below shows an experiment on heat conduction through a piece of iron rod.
Figure 2
Which of the following thumbtacks will fall first?
A. PC. R B. QD. S
• HEAT ENERGY
A hot object has more heat
Sun – primary source of heat energy
A cold object has less heat
1
2
5
3
4
Heat vs Temperature
Other source of heat?
Friction
rubbing two hands together
2. Combustion /burning
burning of candles
Electricity
rice cooker
Uses
Cooking
Drying clothes
Keep us warm
Causes breeze
5. Solar energy