Heat Study Guide
Name ___________________________
Heat is a form of energy that moves from one object to another. Heat can travel
through solids, liquids, and gases.
Heat always travels from a warmer object to a cooler one.
The Sun is Earth’s main source of heat.
Fires use fuels, such as wood, to make heat and light. Burning something causes
it to release heat.
Rubbing two objects together can produce heat. This is why your hands get
warm when you rub them together.
Running electricity through some object can produce heat. Light bulbs, toasters,
and some stoves use electricity to produce heat.
Dark-colored objects absorb most of the light and heat that strike them.
Light-colored objects reflect, or bounce off, most of the light and heat that strike
them. That is why wearing white clothes in the summer can keep cool.
A material that heat moves through easily is called a conductor. Materials like
metals are good conductors. Pots are often made of metal because heat moves
from the stove to the metal pot to cook the food.
An insulator is a material that heat does not move through easily. Wool, cotton,
and fur are examples of insulators. Snow can be an insulator.
All objects are made of tiny particles. The particles are always moving. The
energy that makes them move is called thermal energy. Heating an object
increases how much thermal energy the particles have. Hot objects have a lot of
thermal energy. Its particles move quickly. A cold object, such as an ice cube,
has much less thermal energy. Its particles move slowly.
When heat flows through an object, its particles expand, or get bigger. When
heat flows out of an object, its particles move more slowly and the object gets
smaller, or contracts.
Temperature is how hot or cold something is. A thermometer is a tool used to
measure temperature.
Heat can cause objects to change state. Solids, such as ice cream, can melt when
they are heated. To melt means to change from a solid to a liquid. Liquids, such
as water, can evaporate when they are heated. This means they change into a
gas.
To freeze means to change from a liquid to a solid. When water’s temperature
reaches 32 degrees Fahrenheit, it freezes.
To boil is to change from a liquid to a gas. Energy from heat causes the particles
to move faster. Water boils at 212 degrees Fahrenheit. Most objects expand
when they gain thermal energy.