If a ball is thrown upward at 9696 feet per second from a height of 44 ​feet, the height of the ball can be modeled by Sequals=44plus+9696tminus−16t squaredt2 ​feet, where t is the number of seconds after the ball is thrown. How long after the ball is thrown is the height 112112 ​feet?

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Part 1
It takes enter your response here seconds for the ball to reach the height 112112 feet.
​(Type an integer or a simplified fraction. Use a comma to separate answers as​ needed.)

1 answer

To find out how long after the ball is thrown it reaches a height of 112112 feet, we start with the height equation:

\[ S(t) = 44 + 9696t - 16t^2 \]

We set \( S(t) \) equal to 112112:

\[ 112112 = 44 + 9696t - 16t^2 \]

Now, rearranging the equation gives us:

\[ 0 = -16t^2 + 9696t + 44 - 112112 \]

Simplifying further:

\[ 0 = -16t^2 + 9696t - 112068 \]

To make calculations easier, we can multiply the equation by -1:

\[ 0 = 16t^2 - 9696t + 112068 \]

Now we can solve this quadratic equation \( 16t^2 - 9696t + 112068 = 0 \) using the quadratic formula:

\[ t = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]

Where:

  • \( a = 16 \)
  • \( b = -9696 \)
  • \( c = 112068 \)

Calculating the discriminant (\( b^2 - 4ac \)):

\[ b^2 = (-9696)^2 = 93931376 \] \[ 4ac = 4 \times 16 \times 112068 = 7161088 \] \[ b^2 - 4ac = 93931376 - 7161088 = 86770288 \]

Now we compute:

\[ t = \frac{9696 \pm \sqrt{86770288}}{32} \]

Calculating \( \sqrt{86770288} \):

\[ \sqrt{86770288} \approx 2944.42 \]

Now substituting back into the formula:

\[ t = \frac{9696 \pm 2944.42}{32} \]

Calculating the two possible values for \( t \):

  1. Using the positive root: \[ t_1 = \frac{9696 + 2944.42}{32} \approx \frac{12640.42}{32} \approx 394.38 \]

  2. Using the negative root: \[ t_2 = \frac{9696 - 2944.42}{32} \approx \frac{6751.58}{32} \approx 210.36 \]

Thus, the time it takes for the ball to reach the height of 112112 feet is approximately:

\[ t \approx 394.38, 210.36 \]

For completeness, depending on the context, it is usually only the positive time that is considered meaningful in these problems.

Therefore, the answer for \( t \) is approximately:

394.38 seconds and 210.36 seconds.

So you would need to state:

It takes approximately 394.38 seconds (or 210.36 seconds) for the ball to reach the height of 112112 feet.