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Exercises

  1. Suppose that the the velocity of an object traveling in one dimension is given by $v(t) = t+sin(t)$ for $0 \leq t \leq 6$. Let $s(t)$ be the position of the object at time $t$, assuming that $s(0)=0$.
    1. As explained in your text, the position of the object at $t=6$ is equal to the area under the velocity curve from $t=0$ to $t=6$. Use the midpoint rule with $20$ subdivision to approximate the position of the object at $t=6$.
    2. Let $R_n$ be the right endpoint rule and $L_n$ the left endpoint rule approximations with $n$ subdivisions to the position of the object at $t=6$. Explain why the following relation holds for any value of $n$.

      \begin{displaymath}L_n < s(6) < R_n \end{displaymath}

      (Hint - look at the results of leftbox and rightbox commands.)
    3. Evaluate $R_{500}$ and $L_{500}$. Based on your results, do you think your approximation using the midpoint rule with $20$ subintervals was within $0.1$ of the exact value for the area? Explain why or why not.
  2. Consider the function

    \begin{displaymath}g(x) = \frac{x^2+4x+1}{x^2+2x} \end{displaymath}

    on the interval $[1,5]$.
    1. Use the error bound formula to find the smallest value of $n$ that guarantees that $M_n$ approximates the area to within $0.0005$. That is, find the smallest value of $n$ that guarantees that $\mid EM_n
\mid < 0.0005$.

    2. The value of $n$ given by the error bound is usually conservative. That is, in practice the desired accuracy can be achieved with a smaller value of $n$. Given that

      \begin{displaymath}\int_1^5 g(x) \, dx \approx 6.075665746 \end{displaymath}

      find the smallest value of $n$ such that $\mid EM_n
\mid < 0.0005$.


next up previous
Next: About this document ... Up: Labs and Projects for Previous: Area Approximations
Jane E Bouchard
2001-03-19