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Chapter 5: Section 3 Energy Transformations and Conservation

Author: Mark Biancuzzo

Energy Transformations and Conservation

Niagara Falls is the center of a network of electrical power lines. Water diverted above the falls is used to generate electricity for much of the surrounding region.

Energy Transformations

Mechanical energy of moving water can be transformed into electrical energy

Most forms of energy can be transformed into other forms of energy

Energy transformation – a change from one form of energy to another

Some energy transformations involve single transformations and some involve many transformations

Single Transformations

One form of energy can be transformed into another form of energy to get work done

Example: toaster – electrical energy to thermal energy to toast bread, chemical energy in food to thermal energy to help your body maintain proper body temperature

Multiple Transformations

Sometimes a series of energy transformations is needed to do work

Example: mechanical energy to strike a match, thermal energy to release stored chemical energy, then thermal energy and electromagnetic energy causes the light from the match

Transformation Between Potential Energy and Kinetic Energy

One of the most common energy transformations is the transformation between potential energy and kinetic energy/

Waterfalls = potential energy (PE) transforms into kinetic energy (KE). The water at the top of the falls has gravitational potential energy and as the water plunges over the falls, its velocity increases and the PE becomes KE.

Energy Transformation in Juggling

Juggling balls involves the change from PE to KE and from KE to PE as the balls move in a circular motion being tossed in the air. At the highest point, the ball stops moving and has potential energy. As it falls, the KE increases and the PE decreases.

Energy Transformation in a Pendulum

Continuous PE and KE transformation takes place in a swinging pendulum.

At the highest point in the swing, it has the greatest Gravitational PE. As it swings downward, it speeds up and the PE is transformed into KE. The pendulum has its greatest KE at the bottom of its swing. As it continues to swing, the pattern of transformation of energy continues.

Energy Transformation in a Pole Vault

A pole-vaulter = kinetic energy, transformed into elastic potential energy (the bend in the pole), which then becomes gravitational potential energy. As he comes down over the bar, the GPE is transformed into KE as he falls back to the floor.

 

Pole Vaulting Example

A pole-vaulter = kinetic energy, transformed into elastic potential energy (the bend in the pole), which then becomes gravitational potential energy. As he comes down over the bar, the GPE is transformed into KE as he falls back to the floor.

Conservation of Energy

 

 The Law of Conservation of Energy – energy cannot be created or destroyed

The total amount of energy is the same before and after any type of transformation

Conservation of Energy Song

Energy, Friction, and Matter

Energy and Friction

Whenever an object experiences friction, some of its kinetic energy is transformed into thermal energy.

Example: rubbing your hands together

Energy and Matter

Matter is anything that has mass and takes up space. All objects are made up of matter.

Einstein’s theory – energy can sometimes be created by destroying matter

Destroying just a small amount of matter releases a huge amount of energy.