Chapter 7 Heat - Science Form 1

1. CHAPTER 7HEAT 7.1 HEAT AS A FORM OF ENERGY

3. CHAPTER 7 HEAT

4. 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

5. SOURCES OF HEAT 1. Friction rubbing two hands together 2. Combustion /burning burning of candles Electricity rice cooker

6. 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

7. A thermal infrared image of a hair dryer and a flourescent light bulb ELECTRICITY

8. When a substance is burned , heat is also released Burning firewood COMBUSTION/BURNING

9. USES OF HEAT IN DAILY LIFE Cooking Drying clothes Keep us warm Causes breeze (sea breeze & land breeze) Solar energy Preserving food

10. HEAT & TEMPERATURE

11. 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.

13. 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

14. 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

15. 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