The Fundamental Theorem of Calculus
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4.5   
1. To explore Part I of the Fundamental Theorem graphically, first suppose that F(x) is increasing on the interval [a, b]. Explain why both of the expressions F(b)-F(a) and will be positive. Further, explain why the faster F(x) increases, the larger each expression will be. Similarly, explain why if F(x) is decreasing both expressions will be negative.
2. You can think of Part I of the Fundamental Theorem in terms of position s(t ) and velocity v(t ) = s'(t ). Start by assuming that v(t ) 0. Explain why gives the total distance traveled, and explain why this equals s(b)-s(a). Discuss what changes if v(t ) < 0.
3. To explore Part II of the Fundamental Theorem graphically, consider the function . If f (t ) is positive on the interval [a, b] , explain why g' (x) will also be positive. Further, the larger f (t ) is, the larger g'(x) will be. Similarly, explain why if f (t ) is negative then g'(x) will also be negative.
4. In Part I of the Fundamental Theorem, F can be any antiderivative of f . Recall that any two antiderivatives of f  differ by a constant. Explain why F(b) - F(a) is well-defined; that is, if F1 and F2 are different antiderivatives, explain why F1(b) - F1(a) = F2(b) - F2(a). When evaluating a definite integral, explain why you do not need to include “ +c ” with the antiderivative.
In exercises 5-30, use Part I of the Fundamental Theorem to compute each integral exactly.
5. 6.
7. 8.
9. 10.
11. 12.
13. 14.
15. 16.
17. 18.
19. 20.
21. 22.
23. 24.
25. 26.
27. 28.
29. 30.
In exercises 31-40, use the Fundamental Theorem if possible or estimate the integral using Riemann sums. (Hint: Six problems can be worked using antiderivative formulas we have covered so far.)
31. 32.
33. 34.
35. 36.
37. 38.
39. 40.
In exercises 41-46, find the derivative f '(x).
41.
42.
43. 44.
45. 46.
In exercises 47-54, find the given area.
47. The area above the x - axis and below y = 4 - x2
48. The area above the x - axis and below y = 4x - x2
49. The area below the x - axis and above y = x2 - 4
50. The area below the x - axis and above y = x2 - 4x
51. The area of the region bounded by y = x2, x = 2 and the x - axis
52. The area of the region bounded by y = x3, x = 3 and the x - axis
53. The area between y = sin x and the x - axis for 0 x
54. The area between y = sin x and the x - axis for -/2
In exercises 55-58, find an equation of the tangent line at the given value of x.
55.
56.
57.
58.
59. Use the derivative in exercise 55 to locate and identify all relative extrema of .
60. Katie drives a car at speed mph and Michael drives a car at speed g(t ) = 50+2t  mph at time t minutes. Suppose that Katie and Michael are at the same location at time t = 0. Compute and interpret the integral in terms of a race between Katie and Michael.
In exercises 61 and 62, (a) explain how you know the proposed integral value is wrong and (b) find all mistakes.
61.
62.
In exercises 63-70, find the position function s(t ) from the given velocity or acceleration function and initial value(s). Assume that units are feet and seconds.
63. v(t ) = 40-sin t, s(0) = 2
64. v(t ) = 30+4cos 3t, s(0) = 0
65. v(t ) = 25(1-e-2t ), s(0) = 0
66. v(t ) = 10e-t , s(0) = 2
67. a(t ) = 4-t, v(0) = 8, s(0) = 0
68. a(t ) = 16-t 2, v(0) = 0, s(0) = 30
69. a(t ) = 24+e-t , v(0) = 0, s(0) = 0
70. a(t ) = 3e-2t , v(0) = -4, s(0) = 0
71. If (t ) is the angle between the path of a moving object and a fixed ray (see the figure on the next column), the angular velocity of the object is (t ) = ' (t ) and the angular acceleration of the object is (t ) = ' (t ).

 

Suppose a baseball batter swings with a constant angular acceleration of (t ) = 10 rad/s 2. If the batter hits the ball 0.8 s later, what is the angular velocity? The (linear) speed of the part of the bat located 3 feet from the pivot point (the batter's body) is v = 3. How fast is this part of the bat moving at the moment of contact? Through what angle was the bat rotated during the swing?
72. Suppose a golfer rotates a golf club through an angle of 3/2 with a constant angular acceleration of rad/s 2. If the clubhead is located 4 feet from the pivot point (the golfer's body), the (linear) speed of the clubhead is v = 4. Find the value of that will produce a clubhead speed of 100 mph at impact.
73. From 1970 to 1974, the function 16.1e0.07t  closely approximated the number of billions of barrels of oil consumed in the United States, where t = 0 corresponds to 1970. When pricesrose in 1974, the consumption was approximated by the function 21.3e0.04(t-4). Show that both functions give (approximately) the same consumption value for 1974. Compute and and compute the amount of oil saved by the reduced consumption.
74. The amount of work done by a force F(x) moving an object from x = a to x = b is given by . As the object continues to move, the endpoint changes in time. Then b = b(t ) and the work done is a function of time. The derivative of this function defines power. Show that the power equals F(b(t )) b' (t ).
In exercises 75 and 76, use the result of exercise 74 to compute the horsepower in the following situations. (Note: 1 hp = 550 ft-lb/s.)
75. F(x) = 1000 lb, b' (t ) = 130
76. F(x) = 1000e-x lb, b' (t ) = 100-t  ft/s
In exercises 77-82, find the average value of the function on the given interval.
77. f (x) = x2-1, [1, 3] 78. f (x) = x2+2x, [0, 1]
79. f (x) = 2x-2x2, [0, 1] 80. f (x) = x3-3x2+2x, [1, 2]
81. f (x) = cos x, [0, /2] 82. f (x) = sin x, [0, /2]
In exercises 83 and 84, use the graph to list (x)dx, (x)dx and (x)dx in order, from smallest to largest.
83.

84.

85. Derive Leibniz' Rule = x 'x - x 'x.
86. Suppose that a communicable disease has an infection stage and an incubation stage (like HIV and AIDS). Assume that the infection rate is a constant f (t ) = 100 people per month and the incubation distribution is b(t ) = te-t /30 month -1. The rate at which people develop the disease at time t = T is given by people per month. Use your CAS to find expressions for both the rate r(T) and the number of people who develop the disease between times t = 0 and t = x. Explain why the graph y = r(T) has a horizontal asymptote. For small x's, the graph of y = p(x) is concave up; explain what happens for large x's. Repeat this for f (t ) = 100 + 10 sin t  , where the infection rate oscillates up and down.
87. When solving differential equations of the form f (y) for the unknown function y(t ) , it is often convenient to make use of a potential function V(y). This is a function such that . For the function f (y) = y-y3 , find a potential function V(y). Find the locations of the local minima of V(y) and use a graph of V(y) to explain why this is called a “double-well” potential. Explain each step in the calculation
Since , does the function V increase or decrease as time goes on? Use your graph of V to predict the possible values of . Thus, you can predict the limiting value of the solution of the differential equation without ever solving the equation itself. Use this technique to predict if y' = 2-2y.

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