Math Is Fun Forum

tabby

Member

Registered: 2009-12-07

Posts: 2

Motion Formula and quadratic F. ???

1-
A boat heads upstream a distance of 24 miles on a river with th curent running 3 miles per hour. Th trip up and back takes 6 hours.
Assuming the boat maintained a constant speed relative to the wate What is its speed ????

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2-

A roller coaster has an initial 70-foot vertical drop. the speed v of the last car t seconds after it starts this descent can be approximated as v=8.12t, where v is in feet per second. The height of the last car from the bottom of this drop ,in feet, can be estimated by h=-0.8t^2 -10 +70.     At what time does the last car reach the bottom of the
vertical is the speed of the last car at times ?

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Motion Formula and quadratic F. ???

Hi tabby;

Itf the boat had a speed of 9 mph in still water he could make the trip up and back in 6 hours. Of course his average speed is 8 mph.

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