A flashlight is 40.0 cm from a double convex lens. The image of the flashlight is observed at a position 30.0 cm on the other side of the lens. What is the focal length
of the lens?
1) 0.0580cm
2) 10.0cm
3) 13.3cm
4) 17.2cm

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.