My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited
Questions to think about… My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited What are sources of heat? What is temperature? How do things become hot or cold? Are heat and temperature the same?
My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited Heat Heat is a form of energy that makes things hot. Things that give out heat are known as sources of heat. Burning fuels such as wood and gas produces heat. Electrical appliances like electric irons, water heaters and electric ovens are also sources of heat.
Heat The Sun is our main source of heat. It keeps the Earth and living things on Earth warm. My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited
Heat Feeling heat o You can feel whether something is hot or cold with your sense of touch. o However, your skin cannot accurately measure how hot or cold something is. o Your skin can only sense if something is hot or cold by comparing it with how hot or cold your skin was before. My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited If our skin is not an accurate measure of how hot or cold something is, then what can we use?
Temperature Temperature is how hot or cold something is. Thermometers: o These are used to measure temperature. o Thermometers usually have a liquid inside the bulb. The level of the liquid rises or falls according to temperature changes. bulb My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited A thermometer
Temperature Temperature is measured in degree Celsius ( 0 C). There are different types of thermometers for different purposes. A clinical thermometer such as the one above is used to measure temperatures a few degrees below and above the body temperature of 37 0 C. My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited placed under armpit or tongue A digital thermometer like the one on the left can measure the temperature of our surroundings. A laboratory thermometer is used to measure temperature in Science experiments.
Temperature Reading temperature – how to read correctly: o Step 1: Hold the thermometer upright. o Step 2: Look at the level of the liquid. o Step 3: Position your eyes at the same level as the liquid in the thermometer (see the next slide). o Step 4: Read the marking nearest to the level of the liquid in the thermometer. My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited
Temperature Reading temperature – how to read correctly: My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited
Temperature Heat sensor and datalogger o A heat sensor can be connected to a datalogger. These can be used to measure temperature. heat sensor My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited datalogger
The difference between heat and temperature: Temperature My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited glass Aglass B 60 0 C30 0 C Glass A and glass B have the same amount of water. But the water in glass A has a higher temperature than the water in glass B. To heat up the same amount of water to a higher temperature, more heat is needed. Thus, the water in glass A has more heat than the water in glass B.
Temperature The difference between heat and temperature: glass Cglass D 80 0 C The water in glass C and glass D is at 80 0 C. However, there is more heat in glass C than in glass D since more heat is needed to warm up a greater amount of water. My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited
Heat gain, heat loss Things become hotter when they gain heat. My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited The mug is gaining heat from the hot chocolate. This will cause the temperature of the mug to rise.
Heat gain, heat loss Things become colder when they lose heat. My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited The noodles is losing heat to the surroundings, which will cause the temperature of the noodles to fall.
Heat gain, heat loss Heat always flows from a hotter to a colder place or object. It continues to flow between these two places or objects until both reach the same temperature. My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited