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What is "observable distance from the ground" ?
What is this "constant velocity of 6 ft/s" ? --- I am asking because velocity is not only a magnitude: it is a vector and has its direction, too.
Could you clarify, PLEASE.
Math problem should not be formulated so carelessly . . .
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Also, from the Internet
A typical commercial passenger jet cruises at a speed of about 460 - 575 miles per hour.
So, when you create your own Math problems, try to make it realistic.