The correct answer is: A sub-critical velocity meets a stream moving with a hyper-critical velocity.
A hydraulic jump is a sudden rise in the water level in a stream, caused by a change in the stream’s velocity. It is typically formed when a stream moving with a sub-critical velocity meets a stream moving with a hyper-critical velocity. The sub-critical stream slows down as it approaches the hyper-critical stream, and the water level rises. The hydraulic jump can be a dangerous phenomenon, as it can cause waves and currents that can overturn boats and wash people away.
A hyper-critical velocity is a velocity that is greater than the critical velocity. The critical velocity is the velocity at which a stream of water will flow smoothly over a surface. If the stream’s velocity is greater than the critical velocity, the water will flow turbulently.
A sub-critical velocity is a velocity that is less than the critical velocity. The water will flow smoothly over a surface if the stream’s velocity is less than the critical velocity.
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