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I posted a...; A random thread... talk about whatever
Topic Started: Mar 16 2007, 03:51 PM (104 Views)
Sani
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•FuLL Member•
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I have a profile pic now, but it's not of me, it's of a silver ferrari. I love cars!

Anyone else have something random to say? :kiss:
Solomon Grundy was born on a Monday,
Christened on Tuesday,
Married on Wednesday,
Took ill on Thursday,
Worse on Friday,
Died on Saturday,
Was buried on Sunday,
And that was the end
of Solomon Grundy.

Moral of the story: Life is short. Do something with yours. ;)


Bible Quizzing is awesome, and I said awesome!!!!

You know what? There are a million and one theories about the afterlife... or lack thereof. Only one of them is right. I suggest you make sure that you believe the right one. 'Cause eternity is an awful long time.
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Sani
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How come I'm the only one who comes on here anymore?? lol :angry:
Solomon Grundy was born on a Monday,
Christened on Tuesday,
Married on Wednesday,
Took ill on Thursday,
Worse on Friday,
Died on Saturday,
Was buried on Sunday,
And that was the end
of Solomon Grundy.

Moral of the story: Life is short. Do something with yours. ;)


Bible Quizzing is awesome, and I said awesome!!!!

You know what? There are a million and one theories about the afterlife... or lack thereof. Only one of them is right. I suggest you make sure that you believe the right one. 'Cause eternity is an awful long time.
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Josiah
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So what's new? By the way Sani, your not the only person that comes on anymore, I come on a lot.
And God said, let there be light, and there was.................


LIGHT
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Josiah
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You said I can just about talk about anything!



SCIENCE 807: MACHINES 1
WORK AND ENERGY



You cannot see energy, but you can see what energy does. Energy has no mass, nor does it occupy space. The physical definition of energy is the ability to do work. If work is the motion of an object through a distance, and energy can move an object, then energy and work are related.





Here are your goals for this lesson:

Evaluate the relationship that exists between work and energy
Understand the conversion from potential to kinetic energy and vice versa
Define the term power
Perform calculations to find power




horsepower English system unit of power, equivalent to 746 watts.
kinetic energy Energy of motion.
potential energy Energy of position.
power The rate of doing work.
watt Metric unit of power equal to one joule per second.

Click here to play the Spelling Bee.

Click here to play Alpha14.



Kinetic energy. The energy possessed as the result of the motion of an object is known as kinetic energy. The amount of energy an object in motion possesses depends on its (1) speed and (2) mass. A ball with a mass of 0.25 kilograms and a speed of 80 kilometers per hour has less kinetic energy than a ball with a mass of 1.0 kilograms moving at the same speed. Water rushing downhill has kinetic energy, and a boy going down a ramp on a skateboard also has kinetic energy. Kinetic Energy (K.E.) is directly proportional to the mass and the square of an object's speed.

Potential energy. Stored energy is called potential energy. Any object elevated above the surface of the earth will possess potential energy. "Potential" means ability, so potential energy means the ability to release energy or do work. Why is this?



Recall the example from the previous lesson. A man lifts a box with the force of 1 newton (equal to its weight) 2 meters. The work, therefore, is two joules. This means the energy required to do this was 2 joules.

Now you can understand why the object in Figure 9 has stored energy. Somehow, the energy had to be used (expended) to lift that object to its current position above the ground. If the object weighs 70 newtons, then an equal but opposite force of 70 N had to be applied through a distance of 100 m to place the object on the structure. Perhaps a crane was used.

The energy required = 70 N x 100 m = 7,000 joules.



After the object is set in place, it will have the potential (ability) to release 7,000 joules of energy because:



The energy it now possesses is stored as P.E. until the object is released, dropped, or lowered. If the object is released, all of its P.E. will quickly convert to kinetic energy, and it will hit the ground with impact energy of--you guessed it--7,000 joules.



A marble resting on the edge of a table has potential energy. When it rolls over the edge, the potential energy becomes kinetic energy. The work done to give an object potential energy is found by multiplying its weight (force of gravity) by the height to which it is raised.

Examples of stored energy are water stored behind a dam, a book resting on a table, a child's wagon at the top of a hill, and a pile driver.

Kinetic energy was one of the first types of energy man learned to use. Early in history, people used water turning a wheel to grind wheat, pump water, cut logs, and do many other basic human activities. The kinetic energy of water falling or running down was changed to mechanical energy.

Today the falling water from dams is used to turn turbines that generate electricity. Thus, kinetic energy becomes electrical energy, which might become heat, light, or mechanical energy in homes and factories.







WORK AND POWER



Two men stacking cement blocks will not work at the same rate. Work is the product of a force moving an object through a distance. If each man lifts one hundred 1-newton blocks to a height of 2 meters, each one does the same amount of work. If, however, one man is capable of doing his work faster than the other, the power output of the two men is different.

Power. Three factors determine the amount of power: force, distance, and time. The mathematical form is:


or p = w ÷ t



The rate of doing work is important in many ways. For many activities that are properly called work, time is important. For instance, when a force of 100 newtons is used to lift an anvil to a workbench 1 meter high, how much work is done?

w = f × d = 100 newtons × 1 meter = 100 joules

Power is work divided by time. If four seconds is required to lift the anvil, how much power is developed?



To illustrate the concept of power, let's look at the following example.

Example. Three men are each required to move 100 concrete blocks weighing 10 N each to the top of an office building. The first man carries each block up the outside staircase. He completes the job (work) in 100 minutes. The second man uses a pulley. He completes the work in 50 minutes. The third man uses an elevator. He completes the work in 15 minutes.



Notice that each man does an equal amount of work.
Work = force × distance = weight × height.

× 100 blocks = 1,000 N (total weight)

W = 1,000 N × 25 m = 25,000 joules

W = 25,000 joules

Each man's work is 25,000 joules. Each man, however, does not expend the same power. The power output of each man is as follows:



Because power is determined by how much work or energy is done per unit time, you can see that the power output of the third operation (man) was the greatest. The faster you desire to complete a given amount of work, the more power is required!

Consider an aircraft owner. His aircraft can climb to 10,000 feet in 30 minutes. He wants to modify the craft to reach 10,000 feet in 10 minutes. To do this he must increase the engine's power output.

Units. When James Watt built steam engines in the 1760's, he needed a system upon which to base a rental fee. He compared the engines to strong workhorses that could lift 150 pounds at 3 2/3 feet per second. Watt defined 550 foot pounds per second as one horsepower.



In the metric system, power is expressed in watts, after James Watt. One watt of power is one joule of work performed in one second.



The horsepower unit of the English system is 746 watts.



Today the horsepower is still in common use. All engines and motors have horsepower ratings.
And God said, let there be light, and there was.................


LIGHT
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Sani
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That's copyrighted material. Plus, stop spamming. You're giving yourself post status.
Solomon Grundy was born on a Monday,
Christened on Tuesday,
Married on Wednesday,
Took ill on Thursday,
Worse on Friday,
Died on Saturday,
Was buried on Sunday,
And that was the end
of Solomon Grundy.

Moral of the story: Life is short. Do something with yours. ;)


Bible Quizzing is awesome, and I said awesome!!!!

You know what? There are a million and one theories about the afterlife... or lack thereof. Only one of them is right. I suggest you make sure that you believe the right one. 'Cause eternity is an awful long time.
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Jon
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I had spaghetti for dinner last night. No I'm just kidding. Now that you mention it, at the moment I don't remember what I had for dinner last night. Hmm.... Oh yeah Chinese food. Anyway, since this can be so random I'm being random. :huh:
You know, hmmmm... I don't know. Okay.
An onion a day keeps others away.
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Josiah
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Code:
 
<html>
<head>
<title>My First Web Page</title>
</head>
<body>
<hl>Wow, am I on tv?!</hl>
<p>This is my first Web page.</p>
</body>
</html>
And God said, let there be light, and there was.................


LIGHT
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Josiah
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brdvlbalsbnstsafnalsdth *fights for composure* what?
And God said, let there be light, and there was.................


LIGHT
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