Conservation of Mechanical Energy

A pendulum swings from a high point to a low point. Which of the following best describes the change in energy as it swings downward?

• Kinetic energy increases, potential energy decreases, and total mechanical energy remains constant.

• Kinetic energy decreases, potential energy increases, and total mechanical energy remains constant.

• Kinetic energy increases, potential energy increases, and total mechanical energy remains constant.

• Kinetic energy decreases, potential energy decreases, and total mechanical energy remains constant.

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A 2 kg ball is dropped from a height of 10 meters, assuming no air resistance. Which of the following statements is true just before it hits the ground?

• Its kinetic energy and potential energy are equal.

• Its kinetic energy is at a maximum and its potential energy is at a minimum.

• Its kinetic energy is at a minimum and its potential energy is at a maximum.

• Its kinetic energy is at a minimum and its potential energy is at a minimum.

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Which of the following is true of the conservation of energy in a closed system?

 

• A. Kinetic energy is always conserved.

   

• B. Potential energy is always conserved.

   

• C. Mechanical energy is always conserved.

   

• D. Total energy is always not conserved.

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If mechanical energy is conserved in a system, the energy at any point in time can be in the form of...

•  kinetic energy.

   

• gravitational potential energy

   

• elastic potential energy

   

• all of the above

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3. Mechanical energy is NOT conserved when...

•  A. gravitational potential energy is converted to kinetic energy.

   

• B. kinetic energy is converted ONLY to gravitational potential energy.

   

• C. kinetic energy is converted to JUST elastic potential energy.

   

• D. friction is not negligible.

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NGSS.MS-PS3-5

The mechanical energy of a system of objects is...

• the sum of kinetic energy and gravitational potential energy.

• the sum of kinetic energy and elastic potential energy.

• the sum of kinetic energy and all relevant forms of potential energy.

• the sum of all forms of energy.

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NGSS.MS-PS3-5

The rock rolls down a hill. The potential energy of the rock when it was on top of the hill compared to its kinetic energy at the lowest point is _____.

• equal

• lower

• higher

• not related

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The magnitude of the kinetic and potential energy of a free fall for the first 2 seconds of its fall was given. What is the potential and kinetic energy of the apple before hitting the floor

• PE= 8J; KE = 0

• PE= 8J; KE = 8J

• PE= 0; KE = 8J

• PE= 0; KE = 4J

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NGSS.MS-PS3-2

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At which will the pendulum have the greatest Kinetic Energy?

• A

• B

• C

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A skater starts with 200 J of KE and 1200 J of PEg. What is the total mechanical energy (ME)?

• 900 J

• 1400 J

• 500 J

• 1000 J

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NGSS.MS-PS3-4

NGSS.MS-PS3-5