Calculating Rate of Change of Area in a Growing Circle
Introducing a third variable, time, in determining the rate of change of the area of a circle as both the area and radius evolve over time. Utilizing implicit differentiation, find the derivative of the area with respect to time considering the changing radius.
Calculating Rate of Change of Area in a Growing Circle
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Presentation Transcript
Let’s introduce a “third” variable, time, t The Area of a circle is given by the formula The parameters are A and r
Drop a pebble into a pond Both the Area and radius grow with respect to time
Find the rate of change of the Area with respect to time That is, find:
Notice, the variables do not agree This will be “implicit differentiation” with respect to t. When taking the derivative of A and r we will need to multiply by dA/dt and dr/dt respectively
To find the rate of change of the area with respect to time, we need to know 2 things the radius, r, and its rate of change, dr/dt. This becomes a “related rate” problem in the next section