Applications
The discovery in the experiments is that the initial hypothesis of the counterbalancing
force being dependent on the load’s position is confirmed. However, the
hypothesis “that most kids prefer backpacks lower on their backs” because
“lowering the load’s position will lower the force required” is NOT CONCLUSIVE.
What is CONCLUSIVE is that moving the load closer to the spine will reduce the counterbalancing force. An extension of this observation is to produce a negating force by moving some of the load to the other side of the spine. Figure 25 shows that splitting the initial load and moving some to the front of the spine would reduce the net counterbalancing load greatly. In other word, a FRONTPACK.
A novel design idea would be to create a backpack that has also a FRONTPACK section. By moving some of the load to the front, a person would benefit from a greatly reduced force to balance the load yet supporting the same vertical load. And if it can be made more conclusive as to the effect of positioning the load vertically within the backpack, this new backpack would also have inside compartments that will allow textbooks and other loads to be positioned more strategically.
To test this design idea, a follow-up experiment (see figure 40 and 41) was conducted that incorporated a small lunch bag supported on the front of the researcher. By splitting an initial 20 kg load that was once all in the backpack to a 10 kg front load and a 10 kg back load, the researcher noticed a considerable improvement in her effort to carry the same 20 kg load. In fact the 5 kg front load and 15 kg back load was the most comfortable.
