- #1
cvbrewer
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I am teaching mechanical energy, that is, gravitational potential and kinetic energy, to middle schoolers.
Of course, we have been talking about things like juggler’s pins, roller coasters, and snowboard half-pipes. During this, the kids and I came up with a perplexing question.
When you toss a ball up, it has negative upward acceleration, then it has positive downward acceleration.
Does it “stop” to change direction, or does it go directly from moving up to down without ever pausing? It seemed to me as if it would have to stop rising to start falling, but that left me with the thorny problem of how long it was stopped.
After thinking it over, I had to conclude that it never actually stops, because I couldn’t come up with any rationale at all for determining the amount of time it would stop. Is this addressed by the laws of physics?
Thanks,
CV
Of course, we have been talking about things like juggler’s pins, roller coasters, and snowboard half-pipes. During this, the kids and I came up with a perplexing question.
When you toss a ball up, it has negative upward acceleration, then it has positive downward acceleration.
Does it “stop” to change direction, or does it go directly from moving up to down without ever pausing? It seemed to me as if it would have to stop rising to start falling, but that left me with the thorny problem of how long it was stopped.
After thinking it over, I had to conclude that it never actually stops, because I couldn’t come up with any rationale at all for determining the amount of time it would stop. Is this addressed by the laws of physics?
Thanks,
CV