The horizontal locations of the proximal and distal ends of

The horizontal locations of the proximal and distal ends of a segment are shown for three time points (sampled at 60Hz) in the table below. The center of mass of the segment is located 43% of the segment length from the proximal end. What was the horizontal velocity of the segmental center of mass for frame 2?

Frame     Proximal     Distal

1             1.041            1.104

2             1.524            1.398

3             1.828            1.756

Solution

Frame 1:

length of the segment = 1.104 - 1.041 = 0.063
location of C.O.M = 1.041 + 0.43*0.063 = 1.06809

After 1/60 sec = 0.0166 sec
Frame 2:

length of the segment = 1.524-1.398 = 0.126
location of C.O.M = 1.45218

After 0.0166 sec
Frame 3:

length of the segment = 1.828 - 1.756 = 0.072
location of C.O.M = 1.78696

COM Change frame 2 - frame 1 = 0.38409
COM change frame 3 - frame 2 = 0.33478
velocit = 0.38409/0.0166 = 23.04