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m_a_m_a [10]
3 years ago
7

Ex 7) Imagine a mile-long bar of metal such as the rail along railroad tracks. Suppose that the rail is anchored on both ends an

d that, on a hot day, its length expands by 1 foot. If the added length causes the rail to bow upward in a circular arc, about how high would the center of the rail rise above the ground?
Mathematics
1 answer:
Fantom [35]3 years ago
3 0

9514 1404 393

Answer:

  about 44.5 feet

Step-by-step explanation:

We can write relations for the height of the rail as a function of initial length and expanded length, but the solution cannot be found algebraically. A graphical solution or iterative solution is possible.

Referring to the figure in the second attachment, we can write a relation between the angle value α and the height of the circular arc as ...

  h = c·tan(α) . . . . . . where c = half the initial rail length

Then the length of the expanded rail is ...

  s = r(2α) = (c/sin(2α)(2α) . . . . . . where s = half the expanded rail length

Rearranging this last equation, we have ...

  sin(2α)/(2α) = c/s

It is this equation that must be solved iteratively. We find the solution to be ...

  α ≈ 0.0168538794049 radians

So, the height of the circular arc is ...

  h = 2640.5·tan(0.0168538794049) ≈ 44.4984550191 . . . feet

The rail will bow upward by about 44.5 feet.

_____

<em>Additional comments</em>

Note that s and c in the diagram are half the lengths of the arc and the chord, respectively. The ratio of half-lengths is the same as the ratio of full lengths: c/s = 2640/2640.5 = 5280/5281.

We don't know the precise shape the arc will take, but we suspect is is not a circular arc. It seems likely to be a catenary, or something similar.

__

We used Newton's method iteration to refine the estimate of the angle from that shown on the graph. The iterator used is x' = x -f(x)/f'(x), where x' is the next guess based on the previous guess of x. Only a few iterations are required obtain an angle value to full calculator precision.

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Step-by-step explanation:

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3 0
3 years ago
What is the mean median mode and range of the numbers 31 28 30 31 30 ...?
mamaluj [8]
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5 0
2 years ago
Write an equation of the perpendicular bisector of the segment with the endpoints (8,10) and ( -4,2).
ale4655 [162]

Answer:

The required equation is:

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Step-by-step explanation:

To find the equation of a line, the slope and y-intercept is required.

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Given points are:

(x_1,y_1) = (8,10)\\(x_2,y_2) = (-4,2)

We will find the slope of given line segment first

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Let m_1 be the slope of perpendicular bisector then,

m.m_1 = -1\\\frac{2}{3}.m_1 = -1\\m_1 = \frac{-3}{2}

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(x,y) = (\frac{x_1+x_2}{2} , \frac{y_1+y_2}{2})\\= (\frac{8-4}{2} , \frac{10+2}{2})\\=(\frac{4}{2}, \frac{12}{2})\\=(2,6)

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The equation of line in slope-intercept form is given by:

y = m_1x+b

Putting the value of slope

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Putting the point (2,6) to find the y-intercept

6 = -\frac{3}{2}(2)+b\\6 = -3+b\\b = 6+3 =9

The equation is:

y = -\frac{3}{2}x+9

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Step-by-step explanation:

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Step-by-step explanation:

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