1.Water flows in a river. At 8 a.m. the flow past bridge 1 is 2150cfs. At the same instant the flow past bridge 2 is 1800 cfs. At what rate is water being stored in the river between the two bridges at this instant? Assume zero seepage and negligible evaporation.
2.A solid cylindrical needle of diameter d, lenth L ,and density ρ may float in liquid of surface tension Y. neglect buoyancy and assume a contact angel 0(degree). Derive a formula for he maximum diameter d(max) able to float in the liquid. calculate d(max) for a steel needle ( SG = 7.84)in water at 20C(degree).