Heat and temperature _______________________________________________________________________________________________________________________________________________________________________________________________________________________ 4. Temperature
Figure 7.3This girl has a fever, and it makes her feel really tired. She also feels hot because her temperature is higher than normal. She has a thermometer in her mouth to measure her temperature.
What Is Temperature?
No doubt you already have a good idea of what temperature is.
You might say that it’s how warm or cool something feels.
In physics, temperature is defined as the average kinetic energy of the particles of matter.
When particles of matter move more quickly, they have more kinetic energy, so their temperature is higher. With a higher temperature, matter feels warmer.
When particles move more slowly, they have less kinetic energy on average, so their temperature is lower. With a lower temperature, matter feels cooler.
Measuring temperature
A thermometer is the device that measures temperature.
Many thermometers measure temperature with a liquid that expands when it gets warmer and contracts when it gets cooler.