Water flows through a horizontal pipe of cross-sectional area 10.0 cm 2 at a pressure of 0.250 atm with a flow rate is 1.00 l/s. at a valve, the effective cross-sectional area of the pipe is reduced to 5.00 cm 2. what is the pressure at the valve? the density of water is 1000 kg/m 3, and treat it as an ideal incompressible fluid.

Consider a uniformly charged ring in the xy plane, centered at the origin. the ring has radius a and positive charge qdistributed evenly along its circumference. a)what is the direction of the electric field at any point on the z axis? . b)what is the magnitude of the electric field along the positive z axis? use k in your answer, where k=14πϵ0. d)the ball will oscillate along the z axis between z=d and z=−d in simple harmonic motion. what will be the angular frequency ω of these oscillations? use the approximation d≪a to simplify your calculation; that is, assume that d2+a2≈a2. express your answer in terms of given charges, dimensions, and constants