Which condition must exist in order for conduction to occur between two substances

Abox is pushed down at an angle of 32 degrees on a rough surface. the box moves to the right.what equation should be used to find the net force in the y-direction? answers: a. fnet,y = fn - fgb. fnet,y= fp - ffc. fnet,y = fn-fg- fpcos(32)d. fnet,y = fn-fg-fpsin(32)

With i really need the correct answer!

Consider a one meter long horizontal pipe with a constant 100 cm^2 cross sectional area. water flows rightward into the pipe at x = 0 with flow velocity 02m/sec at every point within the pipe intake area. at x=1, the rightward flow rate is 0.192 m/sec. assume the water is a conserved quantity in the pipe, so there must be a leak (a sink) somewhere in the pipe. 1. compute net volumetric flow of the source if the system to be in equilibrium. 2. now assume the pipe in the problem has no leaks. compute the net volumetric rate of change for the system.