A cross-sectional area of the bulk solid on the belt (m 2, ft 2) v conveyor belt velocity (m/s, ft/s) The cross-sectional area of the bulk solid on the belt can be calculated as. A U b 2 (2) where . U non-dimensional cross-sectional area shape factor. b contact perimeter between bulk material and belt (m, ft) L conveyor length (m) belt elongation, elastic and permanent (%) As a rough guideline, use 1,5 % elongation for textile belts. and 0,2 % for steel cord belts. Note For long-distance conveyors, dynamic start-up calculations. may be required, because not all elements are set in motion simultaneously,