A Related Rates Question.
- Thread starter kitkalin
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- Feb 4, 2004
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First, you correct the first of the two derivative statements you've made. The derivative dP/dt is not 3 "when r = 2", but is always (that is, constantly) equal to 3 meters per second. It is only that you happen to be looking at dP/dt and dr/dt at the instant that r = 2 meters.
You have listed the formula for P in terms of r. You are given dP/dt and r. What did you get when you differentiated the formula for P with respect to time t? What happened when you plugged in the given values? What did you get when you solved for dr/dt? ;-)