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Archive for March 9th, 2008

Pastor D. was preaching an excellent sermon this morning on unity in the church. I heard most of it loud and clear with the abundant and well placed Scripture references. But I missed the last half of the introduction and the first point because of a thought process set in motion by his thought provoking illustration. “…..What makes a battering ram work so well? What if individual soldiers took knives and started cutting sticks off of the log……..What would happen if they went up to the gate one at a time and started beating on it.”

Well, aaaaaactually, thought I, though his analogy was intended to point to the need for unity against the common enemy of the church, the ram works because of momentum which is mass x velocity.  Now the battering ram has plenty of mass but not so much velocity.  If the individual soldiers could produce the velocity of say a tornado the small size of their sticks would not be a problem.  They might well punch holes in the gate.  At lunch I conveyed this lack of attention to the point of the illustration.  Leinadcaro lit up so I indulged the moment.  Somewhere along the line someone figured out that the battering ram works better slung from a frame by ropes or chains.  The frame being mounted on wheels is much easier to move but the real power comes from the increased speed of the swing due to the gravity pulling the ram down.  Leinad responds that angular momentum is involved.  Oh yes, the acceleration due to the gravity becomes the angular momentum of the swing.  If the ropes are longer (bigger frame) the moment of inertia is larger resulting in a larger angular momentum.  Metal ends were added to the ram’s head end at some point increasing the impulse force by decreasing the time of impact because the metal doesn’t compress like the wood (impulse = force x time).  If the metal has one or more sharp ends the pressure exerted increases the force exerted on the gate yet again.  Leinad immediately thought that a charge on the end of the ram would send the explosion through the gate even as modern bunker buster bombs and tank penetrating charges do now.  If not the recoil of the ram due to the charge might finish the job upon its return swing.             
The next point in the sermon was about sound doctrine and a subsequent one concerned freedom to have diversity within the unity of the body.  This reminded me of the Scripture, “He gave some as apostles, some as prophets, some as teachers…..”  The was a purpose for which He did that but some of us get distracted during the sermon by non-spiritual thoughts.  Oh, yeah, it was “for the work of the service”. Sometimes I wonder what service I’m supposed to render.

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