Day 21: What Doesn’t Cause Gravity?

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College-Prep Physics: “What causes gravity?” I got a lot of different answers to that question. Even those who correctly said mass still thought that magnetism, air pressure, and Earth’s rotation played at least some part.

So we did several testing experiments (taken from Preconceptions in Mechanics), pictured above.

1. Magnets: How are magnetism and gravity alike? How are they different? Looking at a table of planetary data, do you see a relationship between a planet’s magnetic field and its gravitational field?

2. Air Pressure: In the jar is spring scale and a weight. What will happen when the vacuum pump removes the air from the jar? Looking at a table of planetary data, do you see a relationship between a planet’s atmospheric pressure and its gravitational field?

3. Rotation: What will happen to the hanging chain when the record player is turned on?  Looking at a table of planetary data, do you see a relationship between a planet’s rotational period and its gravitational field?

Tomorrow we’ll go more in depth about the real cause of gravity.

##BFPM

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About Frank Noschese

HS Physics Teacher constantly questioning my teaching.

3 responses to “Day 21: What Doesn’t Cause Gravity?”

  1. Crawford Heisz (@heisznation) says :

    Do you guys have discussions about momentum and energy being the source of gravity?

    • Frank Noschese says :

      No. I show a video of a homemade Cavendish experiment and we talk about how mass causes gravity. Typically I’ll follow up with a discussion about how Einstein though of gravity as a warping of space-time and a video of a demo showing how marbles on a rubber sheet behave.

    • Frank Noschese says :

      But, blackholes eventually come up and we talk about how light is affected by this warping of space-time.

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