An ideal incompressible fluid flows at 12 m/s in a horizontal pipe. if the pipe widens to twice its original radius, what is the flow speed in the wider section?
a) 4 m/sb) 6 m/sc) 12 m/sd) 3 m/s

Idon’t quite understand this problem

Complete these sentences. if a roller coaster train has a potential energy of 1,500 j and a kinetic energy of 500 j as it starts to travel downhill, its total energy isj. once the roller coaster train gets closer to the bottom of the hill, its kinetic energy increases to 1,100 j, and its potential energy decreases to j. when the train reaches the bottom of the track and is traveling along the ground, its kinetic energy isj.

Why does the liquid rise up through the dip tube when the valve is open