Mechanical Energy Physics

What are the units for energy?

• Watts

• Joules

• Newtons

• meters

What has to be true about an object for it to have kinetic energy?

• it must be moving

• it must be elevated

• it must be experiencing a net force

• it must be accelerating

Tags

NGSS.HS-PS3-2

Does your desk have kinetic energy right now? Explain and justify your answer.

• yes because it is sliding across the room right now

• no because it is not moving

• yes because it has someone sitting in it

• no because it is here on earth

Tags

NGSS.HS-PS3-2

The equation for KINETIC ENERGY is KE = (½)mv^2. If a car with a mass of 2000 kg is traveling at 30 m/s, how much kinetic energy does it have?

• (1/2)(2000)(30)

• (1/2)(2000)(30)^2

• (2000)(30)^2

• (1/2)(30)(2000)^2

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

NGSS.HS-PS2-1

For the last question, what are the UNITS for the answer. (If a car with a mass of 2000 kg is traveling at 30 m/s, how much kinetic energy does it have?)

• N

• m

• J

• W

Tags

NGSS.HS-PS3-2

If a car with a mass of 1000 kg is traveling at 30 m/s, how much kinetic energy does it have?

• (1/2)(1000)(30)

• (1/2)(1000)(30)^2

• (1000)(30)^2

• (1/2)(30)(1000)^2

Tags

NGSS.HS-PS3-1

For the previous two questions, what are the magnitudes of the answers?

• 900,000 J and 450,000 J

• 90 J and 45 J

• 9 J and 4.5 J

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

For the previous two questions, the cars are traveling the same speed. When the MASS of the car was cut in half (2000 -> 1000), what happened to the KE?

• cut in half

• doubles

• quadruples

• cut to 1/4

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NGSS.HS-PS2-3

If a car with a mass of 1000 kg is traveling at 60 m/s, how much kinetic energy does it have?

• (1/2)(1000)(60)

• (1/2)(1000)(60)^2

• (1000)(60)^2

• (1/2)(60)(1000)^2

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

The previous question works out to how much KE?

• 1,800,000 J

• 450,000 J

• 900,000 J

Tags

NGSS.HS-PS3-1