energy, work, and power

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Energy, Work, and Power

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Energy, Work, and Power. Some Definitions. Work= Force X Distance. If a person exerts 20 Newtons of force to move 5 meters, he has done 100 Joules of work. W= 20N X 5m = 100 J. Solve this Problem: A ball weighing three Newtons falls a distance of 4 meters. What work has been done?. - PowerPoint PPT Presentation

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Page 1: Energy, Work, and Power

Energy, Work, and Power

Page 2: Energy, Work, and Power

Some Definitions

Page 3: Energy, Work, and Power

Work= Force X Distance

If a person exerts 20 Newtons of force to move 5 meters, he has done 100 Joules of work.

W= 20N X 5m = 100 J

Page 4: Energy, Work, and Power

Solve this Problem:

A ball weighing three Newtons falls a distance of 4 meters. What work has been done?

Page 5: Energy, Work, and Power

Work Done?

a. A teacher applies a force to a wall and becomes exhausted. Explanation:________________________________________________________________________

Yes or No

b. A weightlifter lifts a barbell over her head. Explanation:________________________________________________________________________

Yes or No

c. A waiter carries a tray full of meals across the dining room at a constant speed. Explanation:________________________________________________________________________

Yes or No

d. A rolling marble down hits a note card and moves it across a table. Explanation:________________________________________________________________________

Yes of No

e. A shot-putter launches the shot. Explanation:________________________________________________________________________

Yes or No

Page 6: Energy, Work, and Power

Let's Practice!

Tap the ball to reveal the assignment

Page 7: Energy, Work, and Power

Mechanical Advantage and Mechanical Efficiency

Both ratios (fractions and percentages) show us how well the machine works.

Page 8: Energy, Work, and Power

Mechanical Efficiency--How well the machine uses the energy you put into it. It compares the work you do to the machine and the work you get out. The work you get out of the machine is always less than the work you put in and you lose some energy to friction.

ME= work outputwork input

X 100

Page 9: Energy, Work, and Power

Mechanical Advantage--How much force you get out of the machine. Your mechanical advantage should be greater than 1 for the machine to be useful.

MA = Force outputForce input

Page 10: Energy, Work, and Power

Attachments

Practice Problems on Work.docx