SOLUTION: In studying the frictional effects on a flywheel, the revolutions per minute R that it makes as a function of the time t (in min) is given by R = 4520(0.750)^2.50t. Find t for R =

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: In studying the frictional effects on a flywheel, the revolutions per minute R that it makes as a function of the time t (in min) is given by R = 4520(0.750)^2.50t. Find t for R =      Log On


   

Question 152698: In studying the frictional effects on a flywheel, the revolutions per minute R that it makes as a function of the time t (in min) is given by R = 4520(0.750)^2.50t. Find t for R = 1950 r/min
Answer by stanbon(75887) About Me  (Show Source):
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In studying the frictional effects on a flywheel, the revolutions per minute R that it makes as a function of the time t (in min) is given by R = 4520(0.750)^2.50t. Find t for R = 1950 r/min
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R = 4520(0.750)^2.50t
1950 r/min = 4520(3/4)^(2.5t)
0.431416 = (3/4)^(2.5t)
Take the log of both sides to get:
(2.5t) = log(0.431416)/log(3/4)
2.5t = -0.365104
t = -0.146042
Comment: This answer doesn't make any sense.
The time should not be negative.
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Cheers,
Stan H.