Motion inside and outside the Unit Boundary
Posted: Thu Oct 13, 2016 11:38 am
Larson's reasoning for determining speed in the time region is somewhat flawed. The logic he uses is that when you move "inside" the unit space boundary, space is fixed at 1 unit and only time progresses. He then concludes that "s" is replaced by "1/t" so speed, s/t becomes (1/t)/t = 1/t2. But "s" isn't replaced--when you are within the unit space boundary, s=1 and because it is at unit speed, he ignores it (just as we ignore "t" in the denominator of speed to get distance... s/1t = s).
The description in RS2 is different, because RS2 recognizes the "geometric reciprocals" of linear and angular velocities. Outside the unit space boundary, you have linear motion from 1->infinity. When you move inside the boundary, geometry inverts to angular motion from 1->0. Linear velocity is expressed mathematically as v1 and angular velocity is orbital, v2. Since s=1 inside the boundary, you end up with 12/t2 = 1/t2, the same as Larson.
The origin of the geometric reciprocal is that in 3 dimensions, lines and planes are "duals." Any (x,y) pair can represent either a line (0,0)->(x,y) or the corners of a plane (0,0)--(x,y). Lines are 1-dimensional structures, planes are 2-dimensional, so that gives the 1st to 2nd power relationship.
The description in RS2 is different, because RS2 recognizes the "geometric reciprocals" of linear and angular velocities. Outside the unit space boundary, you have linear motion from 1->infinity. When you move inside the boundary, geometry inverts to angular motion from 1->0. Linear velocity is expressed mathematically as v1 and angular velocity is orbital, v2. Since s=1 inside the boundary, you end up with 12/t2 = 1/t2, the same as Larson.
The origin of the geometric reciprocal is that in 3 dimensions, lines and planes are "duals." Any (x,y) pair can represent either a line (0,0)->(x,y) or the corners of a plane (0,0)--(x,y). Lines are 1-dimensional structures, planes are 2-dimensional, so that gives the 1st to 2nd power relationship.