A. Designs for a ‘sucking’ chain, with N2 > 0
Fig. 3 shows four link designs where the colliding link pulls
down on the ones above (N2 > 0). Our experiments used the
first of these.
Consider a uniform rod of mass m and length L inclined at
a small angle θ moving vertically downward with velocity v towards
a rigid surface (Fig. 4a). First consider this ‘link’ as not
connected to an upper chain. When the end A hits the surface
the other end B speeds up as required by angular momentum
balance about point A. Assuming a sticking collision (and small
angles), the downwards velocity of B increases to