Question

Why does a stream of water falling straight down from a faucet narrow, and why does a decorative fountain's stream broaden as it rises?

a) Surface tension narrows falling water.
b) Buoyancy broadens rising water.
c) Gravity narrows falling water.
d) Surface tension broadens rising water.

Answer 1

The broadening of a decorative fountain's stream as it rises and the narrowing of a stream of water falling straight down from a faucet can be explained by the principles of fluid dynamics.

Step-by-step explanation:

The broadening of a decorative fountain's stream as it rises and the narrowing of a stream of water falling straight down from a faucet can be explained by the principles of fluid dynamics.

When water is shot nearly vertically upward in a decorative fountain, the stream broadens as it rises due to the decrease in velocity caused by gravity. This decrease in velocity leads to an increase in cross-sectional area, as explained by the continuity equation.

On the other hand, when a stream of water falls straight down from a faucet, it narrows due to the increase in velocity caused by gravity. Again, the continuity equation explains that the decrease in cross-sectional area is a result of the increase in velocity.

Surface tension does not have a direct impact on the broadening or narrowing effect in these cases, as it is primarily related to the cohesive property of liquids.