Warm Up

• 1. What is energy?

• 2. What is chlorophyll?

• 3. What is ecology?

• 4. What is cellular respiration?

• 5. How does a plant get fertilized?

Energy

Energy Conservation

**Energy is a conserved quantity.

**This provides powerful constraints on what can and cannot happen in nature.

This is an extremely important concept, and we will come back to this over and over throughout the remainder of the course.

What is EnergyEnergy: The capacity for doing work (or to

produce heat)

What are some forms/types of energy?1. Mechanical (kinetic and potential energy) 2. Heat3. Electricity 4. Electromagnetic waves 5. Sound6. Nuclear7. Chemical8. Mass

Energy: The capacity for doing work (or to produce heat)

What are some forms/types of energy?1. Mechanical (kinetic and potential energy) 2. Heat3. Electricity 4. Electromagnetic waves 5. Sound6. Nuclear7. Chemical8. Mass

• The thing about energy is that it cannot be created or destroyed, it can only be transformed from one form into another

***Kinetic Energy – Energy of Motion

Kinetic energy (KE) refers to the energy associated with the motion of an object. The kinetic energy is simply:

KE = (½)mv2 where

m = mass in [kg], and v = velocity of object in [m/sec]

What are the units of KE? [KE] = [mass] [velocity]2 = [kg*m2/s2] == [Joule] or just, [J] A Joule is a substantial amount of energy!

Kinetic energy (KE) refers to the energy associated with the motion of an object. The kinetic energy is simply:

KE = (½)mv2 where

m = mass in [kg], and v = velocity of object in [m/sec]

What are the units of KE? [KE] = [mass] [velocity]2 = [kg*m2/s2] == [Joule] or just, [J] A Joule is a substantial amount of energy!

Potential Energy- stored energy

• An object can store energy as the result of its position.

• Examples: gravitational PE, elastic PE, – For example, the heavy ball of a demolition

machine is storing energy when it is held at an elevated position. This stored energy of position is referred to as potential energy.

Gravitational PE

• PE related to an objects height.– GPE=Weight X Height

• Greater the weight, or height, the more GPE the object has.

Chemical Energy

Chemical Energy

PE stored in the chemical bonds that hold chemical compounds together. Stored in the foods we eat (calories), matches you use to light a candle, and even the cells in your body.

PE stored in the chemical bonds that hold chemical compounds together. Stored in the foods we eat (calories), matches you use to light a candle, and even the cells in your body.

Nuclear EnergyNuclear Energy

PE stored in the nucleus of an atom. Nuclear energy is released during a nuclear reactionFor example, nuclear fission, that occurs when a nucleus splits. Nuclear power plants use fission reactions to produce electricity.

PE stored in the nucleus of an atom. Nuclear energy is released during a nuclear reactionFor example, nuclear fission, that occurs when a nucleus splits. Nuclear power plants use fission reactions to produce electricity.

Mass EnergyAccording to Einstein’s Theory of

Special Relativity, Mass is a form of Energy,

and they are related by the simple and well-known formula:

According to Einstein’s Theory of Special Relativity,

Mass is a form of Energy, and they are related by the simple and

well-known formula:

E = mc2

M=MassC= Speed of lightC = 3.0 X 10^8 m/s

E=mc2E=mc2

The important point here is that energy and mass are really equivalent, and are related to one another by simply the speed of light (c) squared!

This equation implies that even if a particle is at rest, it in fact does have a “rest-mass energy” given by this formula.

Can energy change from one type of energy to another?

• Nuclear

• Chemical (photosynthesis)

• Kinetic

• Thermal (maintain body temp)

Electrical ( brain/nervous system)

Chemical

(gas)

Electric

(engine)

Sound

Thermal

Electromagnetic

Mechanical

Solar

Chemical (oil)

Electrical

Kinetic

Nuc

lear

Chemical

Electromagnetic (light, microwave)

Thermal

Kinetic

Sound (radio)

Electricity Electricity generally refers to the flow of charges. In most cases, electrons are the charges which are actually moving. Charges are made to flow by applying a voltage

Batteries Power Supplies Electrical generators