Law of Conservation
- This law states that energy cannot be created or destroyed; it can only be transformed, transferred, or stored.
- The only thing that changes is the form in which the energy appears.
- For example, an apple has chemical potential energy and by eating it gives you energy to move (kinetic energy).
Tracking Energy Transformations
Mountain biking
Imagine that your Grandma got you a new mountain bike for your birthday. It has everything you wanted including a shimmering coat of paint and an awesome set of all-terrain tires! You are so excited to test it out! You take it out the next day for a test ride. As you begin to pedal up the mountain, your leg muscles transform chemical energy into kinetic energy. The kinetic energy of your leg muscles transforms into the kinetic energy of the bicycle. As you advance farther up the mountain, some of this energy transforms into potential energy. The pedaling becomes very challenging as the incline increases and you begin to sweat. Chemical energy from your body is being released, making your body warmer. Because of friction, the mechanical parts of the bicycle are warmer too. Finally, you reach the peak! You should grab a snack to get some chemical energy before you head back down.
Yo-yo
Before the yo-yo begins it falls it has stored energy due to its position. At the top it has maximum potential energy. As the yo-yo starts to fall, the potential energy begins to be transformed into kinetic energy. At the bottom its potential energy has been converted into kinetic energy so that it now has its maximum kinetic energy.
Transforming Chemical Energy
The matter contained in living organisms contains chemical energy. When organisms die, chemical compounds in their biomass break down. Fungi, Bacteria, and other organisms help convert these chemical compounds to simpler chemicals that can be used by other living things. Thermal energy is released as these changes occur. For example, a compost pile can contain plant matter such as grass clippings and leaves. As the compost pile decomposes, chemical energy is converted into thermal energy. This can cause the temperature of a compost pile to reach 60°C.
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