Work and Energy Introduction

What kind of energy is in a moving skateboard?

• Potential

• Kinetic

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Energy cannot be created or destroyed, only converted from one form to another

• true

• false

Answer explanation

You saw this in the pHet Lab. The "lost" energy was converted to useless heat. It wasn't gone. We just couldn't use it to keep moving.

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NGSS.MS-PS3-5

If these are all moving at the same speed, the vehicle with the greatest KE would be

(Think about their masses)

• 
• 
• 
• 

Answer explanation

Kinetic energy not only involves motion, it involves mass. The more mass, the more Kinetic Energy for the same speed.

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Which of the following statements about a skier skiing down a steep slope is true?

• His kinetic energy decreases and his potential energy increases

• His potential energy decreases and his kinetic energy increases

• His chemical energy increases

• Both his potential and kinetic energy increases

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Which of the following objects has kinetic energy?

• A lamp that is turned off

• A bike parked at the top of a hill

• a ball thrown across the yard

• Fallen leaves laying on the ground below a tree

Answer explanation

You are looking for a word that implies motion.... dropped, thrown, pushed, pulled, etc.

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NGSS.MS-PS3-1

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The two types of energy listed under mechanical energy

• kinetic and nuclear

• potential and kinetic

• potential and nuclear

• wind and thermal

Answer explanation

Actually, all types of energy are either kinetic or potential.

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Which letter shows where kinetic energy is at is highest point?

• X

• Y

• W

• Z

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NGSS.MS-PS3-1

Where is kinetic energy at its minimum?

• Z

• W

• X

• Y

Answer explanation

At the very highest point since this is where the energy is completely in the form of Potential Energy.

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A roller coaster is constantly converting PE to KE and back. but why does it slow down as it goes through the course? Mark all that apply.

• Friction with the track slows it down.

• Friction with the air slows it down.

• The people are breathing the air which slows it down

• The Potential Energy slows the cars down.

Answer explanation

Any type of Friction will convert some of the KE and PE energy into useless heat.

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A 6kg cat misjudges a jump and falls 5 meters. How much gravitational potential energy does the cat have? (The cat is fine by the way.)

• 300 J

• 180000 J

• 1225 J

• 3920000 J

Answer explanation

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