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yuradex
3 months ago
11

A 1200-ft equal-tangent crest vertical curve is currently designed for 50 mi/h. A civil engineering student contends that 60 mi/

h is safe in a van because of the higher driver’s-eye height. If all other design inputs are standard, what must the driver’s-eye height (in the van) be for the student’s claim to be valid?

Physics
1 answer:
serg [3.5K]3 months ago
7 0

Response:

8.95ft

Explanation:

For tackling this issue, two key concepts should be evaluated:

First, the design of vertical curves should be considered using the general equation defining the length of a vertical crest curve, based on the differences in gradients. Also, the Design Controls for Crest vertical curves table is useful (a table is attached at the bottom).

The equation for this is written as:

L = \frac{AS^2}{200(\sqrt{h_1}+\sqrt{h_2})^2}

Where,

L = length of vertical curve

S = Sight distance

A = Algebraic difference in gradients

h_1 = Height of eye above road level

h_2 = height of object above road surface

From the provided table, it's determined that at a design speed of 60 mi/h, S measures 570 ft. The vertical curve rate K at a design speed of 50 mi/h is 84.

Next, we can calculate the algebraic difference in gradients as follows:

A= \frac{L}{K}

A = \frac{1200}{84}

A = 14.285

Using the equation to calculate h_1, we find:

L = \frac{AS^2}{200(\sqrt{h_1}+\sqrt{h_2})^2}

1200 = \frac{14.32(570)^2}{200(\sqrt{h_1}+\sqrt{2})^2}

Solving for h_1

h_1 = 8.95ft

Thus, the height of the driver's eye is 8.95ft

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V - wind speed;
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Explanation:

The following information is provided:

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We are to determine the duration taken by the stone to fall a distance of 200 feet, where s = 200 feet

Substituting the value of s into equation (1) yields:

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