everything Light touChes People and other animals need light in order to see Look around you Everything you see is illuminated by a source of light Light is a form of energy Living things need energy to move work and grow Vocabulary When things are illuminated light is shining on them During the day most of our light comes from the sun Without the energy from To reach Earth light from the sun travels about 93 million miles 150 million kilometers 4
Today people use electricity to produce light At night cities like New York glow with electric light the sun there would be no plants or animals on Earth’s surface Before humans learned to harness light on their own nearly all light energy found on Earth came from the sun Eventually humans learned to build fires and then to use electricity This ability to control our environment was a huge step forward for humankind Energy fuels our universe from the stars in the sky to the tiniest algae in the sea Light energy that began its journey out in space allows us to grow our food light our homes and do much more 5
Forms oF energy While light is one form of energy it is not the only one We can feel heat energy given off by fire We hear noises thanks to sound energy All of the foods we eat have chemical energy stored in them Mechanical energy is the energy that a moving object such as a ball that you kicked has because of its movement and position Electrical energy is associated with the flow of tiny particles The chemical energy stored in a person’s muscles can be transformed into the mechanical energy needed to pedal a bike 6
Cars transform the chemical energy stored in gasoline What other things run on gasoline called electrons between atoms Atoms are the tiny units that make up everything in the universe Energy can be transformed or changed from one form to another Lightbulbs let us transform electrical energy to light energy Chemical energy from burning gasoline transforms into mechanical energy that powers our cars and trucks The electrical energy from a lightning bolt can strike the ground and give off heat energy Think About It What are some examples of different forms of energy that you have noticed around you 7
