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Untitled Page 23

  • Page ID
    148363
  • Homework Problems

    1. Write a computer program similar to the one in example 53 on page 74 to evaluate the definite integral

    eq_e8619d0b.png

    (solution in the pdf version of the book)

    2. Evaluate the integral

    eq_64e0aefd.png

    and draw a sketch to explain why your result comes out the way it does. (solution in the pdf version of the book)

    3. Sketch the graph that represents the definite integral

    eq_ee60b61d.png

    and estimate the result roughly from the graph. Then evaluate the integral exactly, and check against your estimate. (solution in the pdf version of the book)

    4. Make a rough guess as to the average value of sin x for 0<x<π, and then find the exact result and check it against your guess. (solution in the pdf version of the book)

    5. Show that the mean value theorem's assumption of continuity is necessary, by exhibiting a discontinuous function for which the theorem fails. (solution in the pdf version of the book)

    6. Show that the fundamental theorem of calculus's assumption of continuity for x· is necessary, by exhibiting a discontinuous function for which the theorem fails. (solution in the pdf version of the book)

    7. Sketch the graphs of y=x2 and y=√x for 0≤ x≤ 1. Graphically, what relationship should exist between the integrals \int01 x2dx and \int01 √xdx? Compute both integrals, and verify that the results are related in the expected way.

    8. Evaluate \int√bx√{x}dx, where b is a constant. (solution in the pdf version of the book)

    9. In a gasoline-burning car engine, the exploding air-gas mixture makes a force on the piston, and the force tapers off as the piston expands, allowing the gas to expand. (a) In the approximation F=k/x, where x is the position of the piston, find the work done on the piston as it travels from x=a to x=b, and show that the result only depends on the ratio b/a. This ratio is known as the compression ratio of the engine. (b) A better approximation, which takes into account the cooling of the air-gas mixture as it expands, is F=kx-1.4. Compute the work done in this case.

    hw-piston.jpg

    k / Problem 9.

    10. A certain variable x varies randomly from -1 to 1, with probability distribution dP/dx=k(1-x2).
    (a) Determine k from the requirement of normalization.
    (b) Find the average value of x.
    (c) Find its standard deviation.

    11. Suppose that we've already established that the derivative of an odd function is even, and vice versa. (See problem 30, p. 50.) Something similar can be proved for integration. However, the following is not quite right.

    Let f be even, and let g=\int f(x)dx be its indefinite integral. Then by the fundamental theorem of calculus, f is the derivative of g. Since we've already established that the derivative of an odd function is even, we conclude that g is odd.

    Find all errors in the proof. (solution in the pdf version of the book)

    12. A perfectly elastic ball bounces up and down forever, always coming back up to the same height h. Find its average height.

    hw-holditch.jpg

    l / Problem 13.

    13. The figure shows a curve with a tangent line segment of length 1 that sweeps around it, forming a new curve that is usually outside the old one. Prove Holditch's theorem, which states that the new curve's area differs from the old one's by π. (This is an example of a result that is much more difficult to prove without making use of infinitesimals.)

    (c) 1998-2013 Benjamin Crowell, licensed under the Creative Commons Attribution-ShareAlike license. Photo credits are given at the end of the Adobe Acrobat version.