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3.6: Derivatives as Rates of Change

  • Page ID
    144210
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    1. The position of a drone flying along a straight line is given by the function \(x(t) = 2t^3 - 6t\), where \(t\) is in seconds and \(x(t)\) is in meters.
       
      1. What is the initial velocity of the drone?
         
      2. What is the drone's velocity after \(t = 1\) second?
         
      3. What is the initial acceleration of the drone?
         
      4. What is the drone's acceleration after \(t = 1\) second?
         
    2. A ball is dropped from the top of a building 256 feet tall. The ball's height in feet above the ground \(t\) seconds after it is released is given by \(y(t) = -16t^2 + 256\) .
       
      1. How long does it take for the ball to hit the ground?
         
      2. What is the velocity of the ball at the moment when it is released?
         
      3. What is the velocity of the ball when it hits the ground?
         
      4. What is the acceleration of the ball at the moment when it is released?
         
      5. What is the acceleration of the ball when it hits the ground?
         
    3. The position in miles of a freight train after \(t\) hours is given by the function \(s(t) = t^3 - 4t\), where east is the positive direction.
       
      1. Determine the direction and speed of the train when \(s(t) = 0\).
         
      2. Determine the direction and speed of the train when \(a(t) = 0\).
         
    4. A small town in Ohio commissioned an actuarial firm to conduct a study that modeled the rate of change of the town's population. The study found that the town's population can be modeled by the function \(P(t) = -\dfrac{1}{3}t^3 + 64t + 3000\), where \(t\) is measured in years.
       
      1. Find \(P'(1)\), \(P'(2)\), \(P'(3)\), and \(P'(4)\). Interpret what the results mean for the town's population.
         
      2. Find \(P''(1)\), \(P''(2)\), \(P''(3)\), and \(P''(4)\). Interpret what the results mean for the town's population.
         
    5. A culture of bacteria grows in number according to the function \(N(t) = 3000\left(1 + \dfrac{4t}{t^2 + 100}\right)\), where \(t\) is measured in hours.
       
      1. Find the rate of change of the number of bacteria, \(N'(t)\).
         
      2. Using a calculator, find \(N'(0)\), \(N'(10)\), \(N'(20)\), and \(N'(30)\). Interpret what the results imply about the bacteria population.
         
      3. Find \(N''(t)\).
         
      4. Using a calculator, find \(N''(0)\), \(N''(10)\), \(N''(20)\), and \(N''(30)\). Interpret what the results imply about the bacteria population.
         
    6. The cost in dollars for a company to manufacture \(x\) food processors is given by \(C(x) = 200 + \dfrac{7}{x} + \dfrac{x}{27}\).
      1. Find the marginal cost of manufacturing 12 food processors. Using your result, estimate the cost of producing the thirteenth food processor.
         
      2. Find the actual cost of manufacturing the thirteenth food processor.​
        ​​​​​​​
    7. The total revenue (in dollars) that a company makes for manufacturing and selling \(x\) digital clock radios is \(R(x) = 10x - 0.001x^2\).
      ​​​​​​​
      1. Find the marginal revenue function.
         
      2. Calculate the marginal revenue for \(x = 2000\) and \(x = 5000\). Interpret your results.

    3.6: Derivatives as Rates of Change is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

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