Water leaking onto a floor forms a circular pool. The area of the pool increases at a rate of 16picm2/min. How fast is the radius of the pool increasing when the radius is 7cm?
Q. Water leaking onto a floor forms a circular pool. The area of the pool increases at a rate of 16picm2/min. How fast is the radius of the pool increasing when the radius is 7cm?
Area Formula: The area A of a circle is given by the formula A=πr2, where r is the radius of the circle. We are given that the area of the pool increases at a rate of 16picm2/min, which is dtdA=16picm2/min. We need to find the rate at which the radius r is increasing, which is dtdr, when the radius is 7cm.
Chain Rule Application: To find dtdr, we will use the chain rule from calculus, which relates the rates of change of two related quantities. Differentiating both sides of the area formula with respect to time t, we get dtdA=dtd(πr2). Applying the chain rule, we get dtdA=2πr⋅dtdr.
Substitution and Calculation: We can now solve for dtdr by substituting the given rate of change of the area and the radius at the moment we are interested in. We have dtdA=16pi cm2/min and r=7cm. Plugging these values into the equation, we get 16=2π⋅7⋅dtdr.
Isolating dtdr: Solving for dtdr, we divide both sides of the equation by 2π×7 to isolate dtdr. This gives us dtdr=(2π×7)16.
Final Calculation: Now we perform the calculation: dtdr=2⋅π⋅716=14π16=7π8 cm/min.
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