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# Work, Energy, and Power PowerPoint PPT Presentation

Work, Energy, and Power. Work = W. The product of the force F applied to an object over a distance d in which the object travels as a result of the force. (Force and distance must be parallel to each other). Joule (J) is the base unit of work. Work Example.

Work, Energy, and Power

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## Work, Energy, and Power

### Work = W

The product of the force F applied to an object over a distance d in which the object travels as a result of the force

(Force and distance must be parallel to each other)

Joule (J) is the base unit of work

### Work Example

A student lifts a 50 pound (lb) ball 4 feet (ft) in 5 seconds (s).

How many joules of work did the student complete?

Convert English units to SI units

Solve for Work

### Energy

Ability to do work

Light, heat, mechanical, chemical, and electrical forms of energy can all be used to exert a force for a distance.

Fuel cell

Roller coaster

NASA solar sail

### Forms of Energy

Potential Energy (Stored energy, usually referring to gravitational energy)

The capacity to do work by virtue of position or configuration

### Forms of Energy

Kinetic Energy (Energy of motion)

Energy which a body possesses because of its motion, which occurs anywhere from an atomic level to that of a whole organism

### Energy Transformation

ChemicalKinetic

Electrical  Thermal

Biomass

Hydropower

Geothermal

Solar

Wind

Natural Gas

Coal

Uranium

Petroleum

### Conservation of Energy

Energy cannot be created or destroyed, but it can change from one form to another.

Energy Conversion

Changing one form of energy to another

Energy Efficiency: The ratio of the useful energy delivered by a dynamic system to the energy supplied to it

Entropy: The increasing disorder when energy is transformed to heat during conversion

### Energy Conversion

Examples

Fossil fuelsChemical→ Heat→ Mechanical→ Electrical

Solar cellsSunlight→Electrical

Wind turbinesKinetic→Mechanical→Electrical

HydroelectricGravitational potential→Mechanical→Electrical

NuclearNuclear →Heat→ Mechanical→Electrical

Vehicle System Conversion

Chemical

Heat

Mechanical

Which output is desired, mechanical or heat?

### What Are Current Energy Concerns?

Consumption

Pollution

Depletion

Dependency

Cost

http://www.eia.doe.gov

What roles do engineers have in energy?

### Power

Rate at which work is performed or energy is expended

Watt is the base unit of Power

One watt is equal to 1 joule of work per second

### Types of Power

Electrical Power

Uses electrical energy to do work

MechanicalPower

Uses mechanical energy to do work (linear, rotary)

FluidPower

Uses energy transferred by liquids (hydraulic) and gases (pneumatic)

### Power Example

A student lifts a 50.0 pound (lbf) ball 4.00 feet (ft) in 5.00 seconds (s).

How many watts of power are used to lift the ball?

Work = 271.45 J

### Resources

McGraw-Hill dictionary of engineering. (2nd ed.). New York, NY: McGraw-Hill.

Microsoft, Inc. (2008). Clip art. Retrieved January 10, 2008, from http://office.microsoft.com/en-us/clipart/default.aspx

National Aeronautics and Space Administration (NASA). (1997). Daedalus. Retrieved April 2, 2008, from http://www.dfrc.nasa.gov/Gallery /Photo/Daedalus/

U.S. Department of Energy. (2008). Scientific forms of energy. Retrieved March 23, 2008, from http://www.eia.doe.gov/kids/energyfacts/science/formsofenergy.html