7 th Grade Science
Energy is the ability to do work or cause change. Work is done when a force moves an object through a distance. Work is the transfer of energy. (The object that work is being done on gains energy) Both energy and work are measured in joules (J). Example: The wind moving a leaf causes change, therefore, the wind has Energy.
Kinetic energy= the energy of motion Potential energy= stored energy
The amount of kinetic energy an object has depends on its mass and velocity. Velocity=how fast an object moves The more work you do to get an object moving, the more energy you give that object.
A bowling ball would have more kinetic energy than a golf ball when traveling at the same velocity, because you would have to do more work to get the ball moving. Kinetic energy increases when velocity increases.
What is kinetic energy?
This type of energy has the potential to do work. There are many types: Elastic, Gravitational, and Chemical are the most common.
Elastic potential energy is associated with objects that can be stretched or compressed. An archer gives potential energy to a bow by pulling it back. This stored energy can send an arrow whistling to its target.
Gravitational potential energy depends on height. The greater the weight of the object or the greater the height its lifted, the greater its gravitational potential energy.
How could this man increase his gravitational potential energy?
Energy stored in atoms that are about to go through a chemical reaction ◦ Food before you eat it, chemicals before they are mixed, etc.
Chemical Electrical Thermal Sound Light Mechanical Nuclear
When you receive a shock from a metal doorknob you experience electrical energy. Moving electric charges produce electricity and they carry electrical energy. We rely on batteries and power lines to run electrical devices such as radios, lights and computers.
Chemical energy is energy that is stored in atoms and the bonds between atoms and can be released by various chemical reactions.energy
A type of potential energy until it is realeased Stored in the nucleus of an atom and released during nuclear reactions. Nuclear power plants use fission reactions to produce electricity. (nucleus splits apart) The sun and other stars create energy through nuclear fusion. (nuclei join together)
Is the measure of the energy of the particles in an object. (atoms and molecules which make up all matter) These particles have both kinetic and potential energy due to their arrangement and motion. When thermal energy increases, its particles move faster making it feel warm to the touch. (Ice cream melts when thermal energy increases.)
Radiant energy is the energy that travels in waves. These waves have electrical properties and magnetic properties. Examples: light we see each day, ultraviolet radiation, microwaves and infrared radiation.
Energy produced from the vibrations of matter. Examples: plucked guitar string, a train horn, someone speaking, etc.
Energy associated with the motion and position of an object. The combination of potential and kinetic energy Examples: frog leaping through the air, swinging a hammer, a spring, bow and arrow, etc.
The Law of Conservation of Energy is very similar to the Law of Conservation of Mass. ◦ Energy cannot be created or destroyed. It can only be transformed from one form to another.
Are energy and work the same thing? How are kinetic and potential energy different? List the forms of energy and give an example of each.