An arch carries the thrust of weight to its (1). With a (2), the horizontal part of the structure supports all the weight above it. A. (1) center; (2) post-and-bearing b. (1) base; (2) springing line c. (1) keystone; (2) groin vault d. (1) sides; (2) post-and-lintel Please select the best answer from the choices provided A B C D.

During the experiment if you could triple the breakaway magnetic force with all other quantities left unchanged, what is the new value for the critical velocity if it was v0 (initial velocity), initially? (b) now if you halved the radius with all other quantities left unchanged, what is the new critical velocity if it was v0 (initial velocity), initially? (c) if during the experiment, critical velocity quadrupled with all other quantities left unchanged, what is the new breakaway force if its magnitude was initially f0,?