4.1a The Sun is a major source of energy for Earth. Other sources of energy include
nuclear and geothermal energy.
4.1b Fossil fuels contain stored solar energy and are considered nonrenewable resources.
They are a major source of energy in the United States. Solar energy, wind, moving water,
and biomass are some examples of renewable energy resources.
4.1c Most activities in everyday life involve one form of energy being transformed into
another. For example, the chemical energy in gasoline is transformed into mechanical
energy in an automobile engine. Energy, in the form of heat, is almost always one of the
products of energy transformations.
4.1d Different forms of energy include heat, light, electrical, mechanical, sound, nuclear,
and chemical. Energy is transformed in many ways.
4.1e Energy can be considered to be either kinetic energy, which is the energy of
motion, or potential energy, which depends on relative position.