Energy, Conservation, and Carbohydrate Storage

Energy and Conservation

Potential energy depends on height; major factor for PE: height.
In a theoretical setup where energy is conserved, total energy stays constant: KE + PE = E_{tot}.
Kinetic energy: KE = \tfrac{1}{2} m v^{2}; Potential energy: PE = m g h.
Therefore: E_{tot} = KE + PE.
This conservation applies in a vacuum with no non-conservative forces; real systems have friction, air resistance, etc., so they are not perfect closed systems.

Energy enters as visible light and is converted by plants into chemical energy stored as glucose.
Plant energy storage examples:
- Starch stores glucose in plants (e.g., potatoes).
- Glycogen stores energy in animals (humans).
- Cellulose is another plant carbohydrate.

Carbohydrates in plants are energy storage, primarily as glucose polymers (e.g., starch).
In humans, energy storage is glycogen.
Plants also use cellulose as a structural carbohydrate.
Wheat processing: remove the embryo (wheat germ) and grind grain to flour for dough (pasta, bread).
The transcript notes that all carbohydrates we eat are stored food for a baby plant; it also states they are all simple sugars. (Note: biologically, carbohydrates include both simple sugars and complex polysaccharides like starch and cellulose.)

Height controls potential energy; energy transfer between KE and PE underlies motion.
Real systems have non-conservative forces; true energy conservation is an idealization.
Photosynthesis links solar energy to chemical energy stored in carbohydrates.
Plant starch and animal glycogen are key storage forms; cellulose provides structure; food processing converts plant carbs into usable forms.