work, energy and power

Motivation and Aperseption

Cycling is a healthy activity.Pedal a bike that requires a power play. Strength is what is called energy.

thenwork, energy and power will be discussed in this chapter.

Happy learning!

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tempo dulu

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COMPETENCY STANDARDS:

Analyze natural phenomena and their arrangement within the scope mechanics object point

BASIC COMPETENCE:

Analyze the relationship between works, changes in energy with the law of conservation of mechanical energy

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Students can calculate the potential energy and the kinetic energy.

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WORK

work are the product of force by the displacement of an object.

W = Fs cos 0 = Fs (1) = Fsfinal positioninitial position

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radiant

nuclear

sound

thermal

Electrical chemical

mechanical magnetic

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ENERGY

Energy is a quantity that is quite important, because energy can not be separated from work. Moving objects and stationary objects turned out to save energy

The energy generated by movement of the object is called kinetic energy

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W = F s W = (m a) s remember: v2

2 = v12 + 2as → as = ½ v2

2 – ½ v12

W = m ( ½ v22 – ½ v1

2 ) W = ½ m v2

2 – ½ m v12

W = Ek2 – Ek1

W = ∆ Ek

F F

s

V1 V2

kinetic energy

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ENERGYEnergy stored in a stationary object at a certain height-called potential energy. mathematically formulated as follows:

EP = m x g x h

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Example

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Car speed changes from zero to 40 m/s , while traveling 1000 m along a runway . If its mass is 20000 kg, find the driving force which needs to be applied to it?

SolotionWork done = gain in kinetic energy

F s = ½ m v2

F X 1000 = ½ 20000 X 402

F = 16000 N

Exercise

1. Kinetic energy possessed a bullet of mass 0.05 kg and traveling at 100 m / s is........a. 2,5 J d. 2500 Jb. 250 J e. 25 000 Jc. 250 J

2. Coconut fruit 1kg mass at an altitude of 12 meters from the ground has potential energy for....a. 0,12 J d. 120 Jb. 1,2 J e. 1200 Jc. 12 J

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thank you for attention

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