When science is hot !
fire! flames! burning! Heat!
The science of heat is important in all kinds of ways. Not only do we cook with heat, but we also warm our homes and heat water. Burning happens in all kinds of engines in cars, trucks, planes and rockets. It is also used in factory processes, from making steel to shaping plastics.
Heat moves by conduction.
(A A firework burns suddenly as an explosive, with heat, light and sound… BANG)
A hot object will pass on, or transfer, some of it’s heat to a cooler one. Dip a metal spoon in a hot drink and spoon handle soon warms up. Heat is-! conducted from the drink, through the metal.
Heat moves by invisible ‘heat rays’.
( Metal is a good conductor of heat. Put a teaspoon in a hot drink and feel how quickly It heats up.)
This is called thermal radiation and the rays are infrared waves. The Sun’s warmth radiates through space as infrared waves, to reach Earth.
burning, also called combustion, is a chemical process.
Oxygen gas from the air joins to, or combines with, the substance being burned.The chemical change releases lots of heat, and usually light too. If this happens really fast, we call it an explosion.
Temperature is a measure of how hot or cold something is.
( A thermometer may be -filled with alcohol and red dye. As the temperature is goes up, the liquid rises up its tube to Show how hot it is. It sinks back down if the temperature falls.)
It is usually measured in degrees Fahrenheit (°F) or Celsius (°C). Water freezes at 32°F (0°C), and boils at 212°F (100°C).We use a thermometer to take temperatures. Your body temperature is about 98.6°F (37°C).
Heat moves by convection, especially through liquids and gases.
(See how hot air shimmers over a candle.)
Some of the liquid or gas takes in heat, gets lighter and rises into cooler areas.Then other, cooler, liquid or gas moves in to do the same. You can see this as ‘wavy’ hot air rising from a flame.
CARRYING HEAT
You will need:
wooden ruler
metal spoon
plastic spatula
heatproof jug
frozen peas
some butter
Find a wooden ruler, a metal spoon and a plastic spatula, all the same length. Fix a frozen pea to one end of each with butter. Put the other ends in a heatproof jug. Ask an adult to fill the jug with hot water. Heat is conducted from the water, up the object, to melt the butter.
Which object is the best conductor?
Answer Give by comment.
When science is hot !
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