Answer to Question #35557 in Molecular Physics | Thermodynamics for MATHAVAN T

Question

When water density increased,"water thrust" increase or decreased?

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Answer 1

1. When water density increased, "water thrust" increased or decreased?
Answer
In simple terms, density is the mass of anything - including water - divided by the volume it occupies. Water density depends on solutes weight, temperature, pressure etc.
More dense, or "heavier" water will slow down objects moving through it more because the object has to, in effect, shove aside more or heavier molecules.
Thus, when water density increased, water resistance force, that acts opposite moving objects increased.
However, screw propellers work by pushing air or water away, and true to Newton’s third law, this motion creates thrust in the opposite direction, propelling the vehicle forward. Therefore, when water density increased, propeller increased thrust.
In water rockets, it works similarly to propellers. Nevertheless, the altitude a rocket reaches in flight also depends on rocket mass, air pressure inside etc.
Thus, if speed and volume of water ejected from the rocket's nozzle in water rocket are the same, water thrust increase when water density increase.