We can not see energy, but we can recognize objects that contain it. Generally speaking , energy is the ability to move an object against an opposing force. It can also be described as the ability to do work.
We know that energy can not
be created or destroyed but it can change from one form into another.
We see examples of such transformations every day. Energy has many forms below are just a few.
Every time you here a sound, what you are listening to is the movement of energy through substances in compression waves.
This is well demonstrated in the video on the right as compression waves, created by the speakers, travel through the air.
Elastic potential energy
Energy stored in elastic materials as the result of stretching or compressing them is known as elastic potential energy. This form of energy is commonly stored in any medium which can be bent, stretched or compressed, such as a diving board, rubber bands, trampolines, bungee chords, springs, or a drawn bow.
is a form of energy which transfers amongst the particles in a substance by increasing the kinetic energy of those particles. In short, heat energy causes particles it travels through to vibrate strongly or speed up.
Chemical potential energy
This form of energy is found stored in the chemical bonds of substances and is released during chemical reactions. Spectacular demonstrations of the release of chemical potential energy are explosions or fireworks.
Without getting into too much detail, we will describe light as the visible energy transmitted via small particles called photons.
Gravitational potential energy
This form of energy is the energy an object possesses because of its position in a gravitational field. Here on Earth, the higher an object is off the ground the greater its gravitational potential energy.
Rivers are sometimes dammed, in hydro-electric schemes, to capture large amounts of water high above the ground and use its gravitational potential energy to create electricity.
This form of energy can loosely be described as the energy carried by electrons in a medium that conducts electricity, such as copper wire.
Objects with mass and motion are said to have kinetic energy. The heavier and faster the object is moving the greater the kinetic energy it possess. Suppose that a train and a racing car are travelling at the same speed, the train has greater kinetic energy because it is heavier.
1) Now suppose the train stopped at the station, which one would have the greatest
kinetic energy the train or the car?
2) Some people argue that sound energy is another form of kinetic energy Explain why this may be so.
3) Would sound energy travel through the vacuum of space? Explain
4) A light globe is connected to a 1.5V battery and then to a 9V battery. It glows more brightly when connected to the 9V battery. This indicates that the 9V battery
5) A round object with a huge mass rolling on the ground will have
6) When a weight lifter lifts the bar above his head he is actually increasing the amount of
of the bar as it remains motionless above his head.
7) Consider the video on the right of a toy plane being wound up. What type of energy is stored?
Now we know that we can not create or destroy energy, however there are many every day examples where by one form of energy is transformed into another.