Lesson Plan - Get It!
- "Ouch! That's hot!"
- "Brr!!! That's Cold!"
- "Things are heating up."
- "That was cool!"
- "Let's warm up those leftovers."
We talk about it, cook with it, complain about it, dress for it, and try to control it. What is this thing called heat?
Throughout history, people have tried to explain the phenomenon of heat.
Today, scientists explain heat by describing the energy in particles (molecules) that make up matter. Not all particles in a substance have the same amount of energy, so some particles move faster and some move more slowly.
Think about this example: If you and your classmates were to walk around a small room, you’d occasionally bump into one another. If you collided with a person moving slower than you, some of your energy would be transferred to that person. The other person would move a little faster, while you’d move a little more slowly.
The same thing happens to particles in matter. As faster-moving particles collide with slower-moving particles, the faster ones lose energy and the slower ones gain energy. However, the total amount of energy always stays the same. The total energy of the particles that make up any matter is called thermal energy.
Heat and temperature are not that same! When particles collide, energy is always transferred from faster-moving particles to slower-moving particles. This flow of energy from warmer matter to cooler matter is called heat.
Temperature is a measure of the average motion of the particles in a substance or object. The faster the particles in matter are moving, the higher the temperature.
But what or where is the source of heat? Most thermal energy on Earth comes from the sun. You can feel your skin get warmer when you are directly in the path of the sun’s rays. But not all thermal energy on Earth comes exclusively from the sun.
Rub your hands together very quickly. Can you feel your hands getting warmer? It comes from the friction between your hands that is generated when you rub them together. The same thing happens when parts of a car engine rub together as the engine runs. As objects move against each other, heat is produced.
Another source of thermal energy can come from electricity. You’ve probably felt the heat that comes from your stove. On electric stoves, the heat comes from electricity. The stove converts electrical energy to heat energy. On a gas stove, heat is produced during the chemical change that occurs when natural gas burns.
The sun, chemical changes, friction (objects rubbing together), and electricity are only some of the sources of heat. Can you think of others? Share your ideas with your teacher or parent.