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The acceleration of a marble in a certain fluid is proportional to the speed of the marble squared and is given (in SI units) by a=-3.00v^2 for v>0. If the marble enters this fluid with a speed of 1.50m/s, how long will it take before the marble's speed is reduced to half of its initial value?

Here's what I think is it...take the derivative of a... a`=6v

d=6(.75m/s)

d=4.5m

I need the acceleration to sub in for the equation vf = vi + at

to find the time.

Am I doing any of this correct?

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# Homework Help: Acceleration in fluid

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