Weighing in

I love teaching physical science. I have three classes of freshmen euphemistically called "Level 1 College Preparatory Physical Science." If a course name has more than a dozen syllables, chances are its geared towards what we used to call the low level students.

Kids end up down here for a variety of reasons, but lack of intelligence is rarely the primary reason. (I am not going to harp on the pedagogical nonsense that all children are capable of being above average. A few kids indeed lack the innate tools to survive the higher level courses.)

I don't exactly teach physics lite, but I do try to minimize the math. We discuss scenarios after reviewing concepts.

The past two days we have been chatting about gravity. Most already knew that you weigh less on the moon--I think that's now culturally ingrained. Democracy is good, America rocks, and you weigh less on the moon.

I then warned the class I was going to ask college level questions (while avoiding the math):

Do you weigh the same on top of Mount Everest
as you do in Bloomfield?

The kids surprised me--a good chunk of them figured out that we actually weigh less on top of Everest, and a couple of them excitedly explained to their neighbors why they thought this was so.



What would happen to you if we could magically
attach a second Earth directly over Bloomfield,
about 20 feet ab
ove the ground?


Again, the kids shone. Faces wiggled as neurons fired. Some were exasperated (and frustrated), but a few of them realized that the net force from the double Earth would be zero, and they could bounce from one Earth to the other by pushing off the ground.

And then the dreaded, wonderful question that the teacher cannot answer--what would you actually feel if your body was simultaneously pulled by two Earths only 20 feet apart? Would you feel anything at all? Would you feel like you were being stretched?

I know I'd have about 200 pounds of force pulling me in opposite directions, but if this force is evenly distributed over my mass, just what would I feel?

Any takers?

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