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Science Form 1 Chapter 7 : Heat
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• When an object is heated, the particles move faster. !
• Particles moves further apart. !
• The object expands
• When an object is cooled, the particles move slower (less energy) !
• The particles moves closer. !
• Contraction process occurs
DemonstrationBall and Ring Experiment
• Initially, the metal ball can go through the ring. !
• When the metal ball is put into hot water, it will expands. It will stuck and can not go through the ring. !
• When the ball is put into the cold water, the particles move closer to each other. The ball is able go through the ring again.
Conclusion
Solid expand when heated and contract when cooled.
DemonstrationMercury expanding and contracting
in thermometer
Demonstration
• When the thermometer, is put into hot water, the temperature will rise. (Mercury inside thermometer is expanding) !
• When the thermometer is put into cold water, the temperature will decrease. (Mercury inside thermometer is contracting)
Mercury expanding and contracting in thermometer
Conclusion
Liquid expand when heated and contract when cooled.
Demonstration
• When the test tube is heated, the bubbles is produced. (The gas particles inside the test tube is expanding and push out through the delivery tube)
Gas expansion and contraction
Conclusion
Gas expand when heated and contract when cooled.
Question 1
What happen when an object is heated?
Answer
The object expands.
Question 2
What happen when a liquid is cooled?
Answer
The liquid contracts.
Question 3
What happen when gases is heated?
Answer
The gases expands.
Heat Flow1. Heat flows in three different ways:
A. Conduction
B. Convection
C. Radiation
Conduction1. Conduction : flow of heat through
solid.
2. Example : You can feel the spoon become hot when stir a hot bowl of soup.
3. Heat flows from higher temperature to lower temperature.
Conduction3. Heat transfer from hot area to cold
area.
4. The BIGGER the different in HEAT, the faster the HEAT flows
Conduction1. Conduction : flow of heat through
solid.
2. Example : You can feel the spoon become hot when stir a hot bowl of soup.
3. Heat flows from higher temperature to lower temperature.
Conduction3. Heat transfer from hot area to cold
area.
4. The BIGGER the different in HEAT, the faster the HEAT flows
Convection1. Convection : flow of heat through
liquid and gas.
2. The hot fluid expands and become less dense (form convection current -a cycle).
3. Heat transfer from hot area to cold area.
Convection1. Convection : flow of heat through
liquid and gas.
2. The hot fluid expands and become less dense (form convection current -a cycle).
3. Heat transfer from hot area to cold area.
Radiation1. Radiation : flows of heat through
empty space or vacuum.
2. The heat transfer in the form of wave.
3. Example : Transfer of heat from the Sun to the Earth.
Question 1
How does heat flows?
Answer
Heat flows from hot area to cold area.
Question 2
Name three ways of heat flows.
Answer
Conduction, convection and radiation
Question 3
What effect heat flows?
Answer
The temperature different.
The BIGGER the different in HEAT, the faster the HEAT flows
