Energy and Power

Energy and Power

by Walid Hafizul

7.1 Work, Energy and Power

7.2 Potential Energy and Kinetic Energy

7.3 Principle of Conservation of Energy​

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​Work

​product of force and displacement in the direction of the force

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W = Fs

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​unit: Joule (J)

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​Energy

​Ability to do work

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​unit: Joule (J)

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Power

​work is done

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Poll

any work done here?

• Yes

• No

Poll

Andrew and Matthew carry an identical sack of apples from the garden to the playground. If Matthew reach the destination before Andrew, who has more power?

• Andrew

• Matthew

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7.2​ Potential Energy and Kinetic Energy

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​Gravitational Potential Energy

​work done to lift an object to a height, h from the Earth's surface

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​E_g = mgh

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​m: mass (kg)

​g: gravitational acceleration (ms^-2)

​h: height (m)

​Work done and Gravitational Potential Energy

​w = Fs

​F is vertically upward, known as Weight

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​w = weight x s

​weight is mg

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​w = mgs

​s is height lifter, h

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​w = mg

Poll

is there any gravitational potential energy on the apples

• Yes

• No

• Doubt

• Prefer not to say

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Elastic Potential Energy

​Work done and Elastic Potential Energy

Elastic potential energy = area under the graph

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Multiple Choice

What kind of energy is stored in the object?

• Gravitational potential energy

• Elastic potential energy

• Kinetic energy

Multiple Choice

What kind of energy is stored in the object?

• Gravitational potential energy

• Elastic potential energy

• Kinetic energy

Multiple Choice

What kind of energy is stored in the object?

• Gravitational potential energy

• Elastic potential energy

• Kinetic energy

​Kinetic Energy

Open Ended

Name something that has kinetic energy

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7.3 Principle of Conservation of Energy​

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​Principle of Conservation of Energy

​Energy cannot be created or destroyed but can only be converted from one to another.

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