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Activity 4.3.4

Avg difficulty 2.5

Suppose that v(t)=4−(t−2)2v(t) = \sqrt{4-(t-2)^2} tells us the instantaneous velocity of a moving object on the interval 0≤t≤40 \le t \le 4, where tt is measured in minutes and vv is measured in meters per minute.

  1. Sketch an accurate graph of y=v(t)y = v(t). What kind of curve is y=4−(t−2)2y = \sqrt{4-(t-2)^2}?

  2. Evaluate ∫04v(t) dt\int_0^4 v(t) \, dt exactly.

  3. In terms of the physical problem of the moving object with velocity v(t)v(t), what is the meaning of ∫04v(t) dt\int_0^4 v(t) \, dt? Include units on your answer.

  4. Determine the exact average value of v(t)v(t) on [0,4][0,4]. Include units on your answer.

  5. Sketch a rectangle whose base is the line segment from t=0t=0 to t=4t = 4 on the tt-axis such that the rectangle's area is equal to the value of ∫04v(t) dt\int_0^4 v(t) \, dt. What is the rectangle's exact height?

  6. How can you use the average value you found in (d) to compute the total distance traveled by the moving object over [0,4][0,4]?

Boelkins, Active Calculus, §4.3 The definite integral, Activity 4.3.4

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