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arcticf0xBest ResponseYou've already chosen the best response.0
http://www.youtube.com/watch?v=oAc4TP0MXBk at 47.00
 2 years ago

arcticf0xBest ResponseYou've already chosen the best response.0
Why the time difference? Its not angle, friction.. what is it?
 2 years ago

arcticf0xBest ResponseYou've already chosen the best response.0
@JamesJ Please share some insight :)
 2 years ago

arcticf0xBest ResponseYou've already chosen the best response.0
In that experiment, there is a difference in his prediction time and actual time. Why is that, as WL asks about it.
 2 years ago

JamesJBest ResponseYou've already chosen the best response.1
Ok. The difference between the two scenarios is whether or not the object oscillating has angular momentum. In the first casewith the air trackthe bob has no intrinsic angular momentum and the situation can be analyzed with just 'translational kinematics'. In the second case, the ball does rotate about an internal axis, it has nonzero moment of inertia and hence it has nonzero angular momentum. Hence there is rotational kinetic energy \[ RKE = \frac{1}{2}I\omega^2 \] and as the ball moves gravity and friction does work on the ball to make it change angular momentum \( \omega \).
 2 years ago

arcticf0xBest ResponseYou've already chosen the best response.0
Oh ok, so its the ball's inertia and rotaion! Does that affect his prediction time aswell?
 2 years ago

JamesJBest ResponseYou've already chosen the best response.1
So work is done on the ball to make it change its angular velocity, and that work takes energy away from the other forms of mechanical energy: translational KE and gravitational PE. yes, it most definitely impacts the physics, so the analysis he did on the board was wrong (and of course he knows it; he's making a point).
 2 years ago

arcticf0xBest ResponseYou've already chosen the best response.0
Oh ok, so he purposely didnt take that work into account! Cool. But hey, does that roation and initial momentum affect his prediction time?
 2 years ago

JamesJBest ResponseYou've already chosen the best response.1
the fact that the object does rotate about its own axis definitely effects the period of oscillation
 2 years ago

arcticf0xBest ResponseYou've already chosen the best response.0
Yes indeed! I got the point(s), thanks for your time James!
 2 years ago

pastoryBest ResponseYou've already chosen the best response.0
p.e math=mgh m=mass g=gravitation h=height
 2 years ago
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