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From: brian whatcott <betwys1@sbcglobal.net>
To: Paul Nord <Paul.Nord@valpo.edu>
Cc: Phys-L@Phys-L.org
Sent: Thursday, June 7, 2012 10:35 AM
Subject: Re: [Phys-L] real-world physics
I fear that I shall need someone to draw a picture: take a case where an
object dropping near Earth is accelerating at -1g and via a very long
buffer is decelerated thru 0 to +1g. Does that object not bounce up?
Where is my misconception? Does -1g to +1 g constitute this doubling? I
am think doubling -1 is -2 or doubling one is two. Would you straighten
me out please?
Brian
On 6/7/2012 9:23 AM, Paul Nord wrote:
If the bubble wrap acts like an ideal spring, completely reversing the motion does imply that a lower limit on the maximum acceleration of 2g.
In this case, it's simpler to consider the duration of the collision. Starting at a speed of 120 mph (50 m/s) and changing that to zero implies an average speed during collision of 25 m/s. Traveling a distance of 4 inches (0.1 m) at this speed means that the collision takes 0.004 seconds. Knowing our delta-v and delta-t we can say that the average acceleration during that time is 12,500 m/s/s (1250 g).
That is the calculation that the Mythbusters should have done before attempting to build this.
Paul
On Jun 6, 2012, at 5:46 PM, brian whatcott wrote:
Hmmm.. with a compressing spring, an increasing force, providing an increasing retardation.
So certainly not constant acceleration. I think I was responding to the idea of doubling the acceleration by the reversed direction, which seems also mistaken
Brian W
On 6/6/2012 11:54 AM, brian whatcott wrote:
Comparable speed at reciprocal heading, with constant acceleration possibly??_______________________________________________
Brian W
On 6/6/2012 10:57 AM, Bernard Cleyet wrote:
On 2012, Jun 06, , at 08:19, John Clement wrote:
I wonder if the boxes were filled with bubble wrap.A possible worsening, as if not popped, bouncing, doubling the acceleration.
Since these are__
professionals I suspect they first tried a dummy and that they know how to
calculate forces.
So testing an idea is not all that farfetched.
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