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BE SURE TO HAVE YOUR ID VISIBLE AROUND YOUR NECK, NO NON-BE SURE TO HAVE YOUR ID VISIBLE AROUND YOUR NECK, NO NON-POLY ATTIRE! POLY ATTIRE!

DRILL: powerDRILL: power Date: Date: Jan 30, 2012Jan 30, 2012How many Joules of work are used by a 100 w bulb in 2 minute?

OBJECTIVEOBJECTIVEDefine and solve word on potential energy. Define and solve word on potential energy. HOMEWORKHOMEWORKCopy and answer no. 10 & 13 of page 292Copy and answer no. 10 & 13 of page 292Note: Quiz on power work & energy on Friday. Feb 3Note: Quiz on power work & energy on Friday. Feb 3

THINK ABOUT!

WHAT IS ENERGY?

EnergyTHE ABILITY TO DO WORK!

TYPES OF ENERGY

• MECHANICALMECHANICAL– Car, plane, wagonCar, plane, wagon

• THERMALTHERMAL– Heat from moving moleculesHeat from moving molecules– Inside all matter; furnaceInside all matter; furnace

• ELECTROMAGNETICELECTROMAGNETIC– Visible light, microwaves, Visible light, microwaves,

radio wavesradio waves

• CHEMICALCHEMICAL– Batteries, matches, Batteries, matches,

body cellsbody cells

• ELECTRICALELECTRICAL– Lightning, power linesLightning, power lines

• NUCLEARNUCLEAR– Nuclear power plants, Nuclear power plants,

atomic bomb, sun & atomic bomb, sun & starsstars

Mechanical EnergyWhen work is done to an object, it acquires energy. The energy it acquires is known as mechanical energy.

How is MECHANICAL energy divided?

PotentialEnergy

KineticEnergy

MECHANICAL ENERGYMECHANICAL ENERGY

GravitationPotentialEnergy

ElasticPotentialEnergy

ChemicalPotentialEnergy

POTENTIAL POTENTIAL ENERGY!ENERGY!

A Roller CoasterAs it slows to a stop

at the top of a hill, it has potential potential energyenergy because of wherewhere it is.

It has the potential to move because it is above the ground and has somewhere to go.

Substances like wood, coal, oil, and gasoline have storedstored energy energy because of their chemistry – they can burnburn

Stored energy isis potential energy

What is Potential Energy?

oEnergy that is stored and waiting to be used later

Potential Energy–Stored chemically in fuel, the nucleus of

atom, and in foods.–Or stored because of the work done on it:• Stretching a rubber band.•Winding a watch.•Pulling back on a bow’s arrow.• Lifting a brick high in the air.

Gravitational Potential Energy

ENERGY THAT DEPEND ON HEIGHT

Gravitational Potential Energy

A waterfall, a suspension bridge, and a falling snowflake all have gravitational potential energy.

Gravitational Potential Energy

If you stand on a 3-meter diving board, you have 3 times the G.P.E, than you had on a 1-meter diving board.

Gravitational Potential Energy

“The bigger they are the harder they fall” is not just a saying. It’s true.

Objects with more mass have greater G.P.E.

The formula to find G.P.E. is

GPE = Fg X h

What is Gravitational Potential Energy?

o Potential energy due to an object’s position

o P.E. = mass x height x

gravity

Don’t look down, Rover!

Good boy!

Elastic Potential Energy• Energy that is stored due to being

stretched or compressed is called elastic potential energy.

What is Elastic Potential Energy?

o Potential energy due compression or expansion of an elastic object.

Notice the ball compressingand expanding

What is Chemical Potential Energy?

o Potential energy stored within the chemical bonds of an object

Potential energy exists whenever an object which has mass has a position within a force field. The most everyday example of this is the position of objects in the earth's gravitational field. The potential energy of an object in this case is given by the relation:

PE = mgh

 PE = Energy (in Joules)

m = mass (in kilograms)

g = gravitational acceleration of the earth (9.8 m/sec2)

h = height above earth's surface (in meters)

QUESTION

If A and B are both the same height,

Do they have the same amount of Potential Energy?

PRACTICE PROBLEM 1A hallway display of energy is constructed in which several people pull on a rope that lifts a block 1 m. The display indicates that 1 Joule of work is done. What is the mass of the block?

PRACTICE PROBLEM 2Antwan raised a 12 N physics book from a table 75 cm above the floor to a shelf 2.15 m above the floor. What was the change in the PE of the system?

CLASSWORKOn a separate sheet of paper, DON’T

COPY QUESTION/ PROBLEM

Part 1. Answer in a complete sentenceNo. 4 [a-b], 6 & 9 of page 267

Part 2. Show work! – knowns & unknowns

No. 44-48 of page 269

WRAP-UP WRAP-UP Copy and answer OR answer in a complete sentenceCopy and answer OR answer in a complete sentence

What are the quantities that describes potential energy? What are the quantities that describes potential energy?

REMINDERS!REMINDERS!

Only absences/ missed work with pink slips can be made upOnly absences/ missed work with pink slips can be made up

MISSING A DETENTION = 0 IN ALL OUTPUTS FOR THAT DAY MISSING A DETENTION = 0 IN ALL OUTPUTS FOR THAT DAY [includes notebook][includes notebook]

COACH CLASS Tues & Thurs, 3:15 – 4:00, RM 127COACH CLASS Tues & Thurs, 3:15 – 4:00, RM 127

QUIZ ON work power & energy on QUIZ ON work power & energy on FEB 3FEB 3

Notebooks will be checked on FEB 3…Notebooks will be checked on FEB 3…