The Law of Conservation of Energy Explained

The video tutorial explores the concepts of conservative and non-conservative forces, focusing on how they affect energy conservation. It explains the law of conservation of mechanical energy and introduces the law of conservation of energy, highlighting the role of non-conservative forces in energy transformation. The tutorial provides practical examples and problem-solving techniques to illustrate these principles.

What is the primary difference between conservative and non-conservative forces?

• Non-conservative forces always increase mechanical energy, while conservative forces always decrease it.

• Conservative forces always increase mechanical energy, while non-conservative forces always decrease it.

• Non-conservative forces can store and release energy equally, while conservative forces cannot.

• Conservative forces can store and release energy equally, while non-conservative forces cannot.

Which of the following is an example of a non-conservative force?

• Static electricity

• Friction

• Elastic force from a spring

• Gravity

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How do non-conservative forces affect mechanical energy?

• They always increase mechanical energy.

• They have no effect on mechanical energy.

• They can either increase or decrease mechanical energy by converting it to or from other forms of energy.

• They always decrease mechanical energy.

What is the law of conservation of energy based on?

• Newton's First Law

• The Work-Energy Theorem

• The Law of Inertia

• The Law of Universal Gravitation

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NGSS.HS-PS3-2

In the snowboarder example, what is the initial kinetic energy if the snowboarder starts at 10 m/s and has a mass of 80 kg?

• 800 J

• 3200 J

• 4000 J

• 1600 J

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NGSS.HS-PS3-1

NGSS.HS-PS3-2

What is the final velocity of the snowboarder if the final kinetic energy is 2770 J and the mass is 80 kg?

• 7.42 m/s

• 8.32 m/s

• 9.12 m/s

• 10.22 m/s

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NGSS.HS-PS3-1

In the sledgehammer example, what is the initial potential energy if the hammer starts at a height of 2.2 meters and has a mass of 5 kg?

• 107.8 J

• 98.0 J

• 112.4 J

• 120.5 J

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NGSS.HS-PS3-1

What is the work done by the man pulling down the sledgehammer with a force of 100 N over 2 meters?

• 150 J

• 200 J

• 250 J

• 300 J

In the bicycle example, what is the final potential energy if the cyclist rises 0.75 meters and has a mass of 90 kg?

• 900 J

• 662 J

• 735 J

• 810 J

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NGSS.HS-PS3-1

What is the force of friction if the work done by friction is -5414 J and the displacement is 8 meters?

• 800 N

• 750 N

• 700 N

• 667 N

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