_Microsoft_Word_-_Finite_Diff_Vector_Kinematics_ -...

Finite-Difference Vector Kinematics
A strobe motion diagram shows an object's
positions at equally-spaced time intervals ± t :
Time interval #1 ² 2 :
± r
12
= r
2
- r
1
Avg. Velocity :
v
12
=
± r
12
± t
± instantaneous v (t) midway thru interval #1 ² 2
(at time t = t
1
+
± t
2
) if ± t is "small" enough
Draw ± r
12
= v
12
± t
. . . etc. for each interval.
1
2
3
4
t = t
1
1
t + ± t
1
t + 2 ± t
1
t + 3 ± t
x
y
z
1
2 r
1
r
2
± r = v ± t
12 12

Time intervals #1 ± 2 and #2 ± 3 :
Avg. Acceleration :
(around point #2)
instantaneous v 's
644474448
a
2
=
²