An object at temperature (in °C) cools in a room held at a constant 20 °C

MATHEMATICS · Multi-part · AP · Calculus AB · Differential Equations · Differential Equations

Problem

An object at temperature T(t)T(t) (in °C) cools in a room held at a constant 20 °C. The temperature satisfies dTdt=−0.1(T−20)\dfrac{dT}{dt}=-0.1\bigl(T-20\bigr) for t≥0t\ge0, where tt is measured in minutes. (a) On the grid of points with tt-coordinates 0,1,2,3,4,50,1,2,3,4,5 and TT-coordinates 10,20,30,4010,20,30,40, compute the value of dTdt\dfrac{dT}{dt} at each point. (b) Use the slopes from part (a) to sketch a slope field covering 0≤t≤50\le t\le5 and 10≤T≤4010\le T\le40. Draw a representative sample of line segments so the overall pattern is clear. (c) A solution curve passes through (0,30)(0,30). Using only the slope field, estimate the object’s temperature at t=5t=5 minutes and explain the steps in your estimation. (d) Interpret in everyday language what the slope field suggests about how quickly the object cools when it is much warmer than the room versus when it is close to room temperature.

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