Ariver is flowing at 3.6 m/s. A boy in a tube is floating the river downstream. If the boy can use his arms to paddle at 1.7 m/s with the current, how fast will it appear he is moving to anyone on
the riverbank?

The total speed is 5.3 m/s

Explanation:

The speed of river = 3.6 m/s

The speed of the tube that a boy use for downstream = 1.7 m/s

Now we have to find the total speed of the boy in the case of downstream. However, in this case, the total speed can be determined by adding both the given speeds.

The total speed = Speed of rive + speed of the tube

Total speed = 3.6 + 1.7

Total speed = 5.3 m/s

your answer would be fusion

that tool is called an altimeter which measures your altitude which can be used to tell which atmosphere you are currently in, including the stratosphere.

hope this ! : )