gordonjudd wrote: ↑
Wed May 13, 2020 3:26 am
I will be most interested in the calculation you come up with to quantify the tangential velocity of the line going around a curved path.
I have devised a 2d equation which, given the incoming and outgoing legs' velocities, works provided the bend's path of travel is aligned with that of the markers on the incoming leg. If not aligned, the 1/2(V1
) or 1/2(V1
) type of approach becomes a complicated waste of time. Moreover, given that one will need for that simpler 2d scenario to measure at least the speed and direction of at least one point on each of the two legs, plus the direction of the bend's travel (to check validity), it will be much simpler to just measure the velocity of a point on either of the legs and that of the bend. The resulting bend-vs-leg or leg-vs-bend relative speed easily and more reliably give the bend's propagation speed and conversely the tangential speed (its magnitude here being the operative interest).
So far, the physics observations I’ve contributed along this experiment were, on the one hand, pointing out the tendency of the rear-most incoming leg’s trajectory dictating bends’ motion in space and on the other hand positing the question of the mid leg’s apparent levitation. I now add a few observations/musings.
With Graeme’s snap cast
previously analysed, the fly leg continually accelerated upwardly (though with decreasing intensity). With the square snaps, the measured fly leg speed for a while decreased apace with the rate of the other legs’ decrease before gradually diverging until finally appreciably accelerating once the fly end has left the ground. Note that Graeme’s snap cast initially had a fly leg speed of virtually zero. In contrast, the square snaps did not, the fly leg already having had considerable speed by the time that the final acceleration by the rod tip was made.