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Topic: relative speeds between two moving objects
Replies: 2   Last Post: Sep 5, 2013 8:03 PM

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Posts: 3,792
From: London
Registered: 2/8/08
Re: relative speeds between two moving objects
Posted: Sep 5, 2013 6:46 PM
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<jaymoseley@hotmail.com> wrote in message
> I was wondering if I could get some help on a math problem .
> Im trying to find out what the correct answer would be for the
> following problem.
> A disc rotates about an axis at a constant speed of rotation.
> On the disc is a capsule 'C' that will eject a ball 'B' onto a track.
> For purposes here, as its a maths problem,lets say the ball
> when released travels in a straight line, at a constant speed
> tangentally away from the rotating disc holding the (rotating)
> capsule. Now, given that the ball is moving at a constant speed
> on the track in a straight line away from the rotating disc
> and capsule. ... Is the ball also ...
> A) moving away from the rotating capsule at a constant speed
> or
> B) moving away from the rotating capsule at a variable speed?

I read you are asking about the relative speed of the ball to the capsule.
Unless I am missing something, the answer is of course B: The ball goes at
constant speed along a line, the capsule goes at the same speed along a
circumference. When the capsule is at the point where the ball was
released, their relative speed (vector difference) will be zero; when the
capsule is at the opposite point on the circumference, their relative speed
will be twice the original speed. Bottom line, the relative speed of the
ball to the capsule oscillates between these two extrema.

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