Using the method of observing the sun s shadow, the longitude of the school location is roughly dete

When I was in college, I once led a classmate from the Astronomical Society to measure it, erect a pole on the ground, and constantly draw its shadow. When the shadow is the shortest, record the direction of the shadow at that time. This is due north.

Measure the length of the shadow and the pole at this time, use trigonometric functions to calculate the elevation angle of the sun, and then consider the number of dates from the spring (autumn) equinox and summer (winter) solstice to measure the day, and use trigonometric interpolation to calculate the latitude of the direct sun point on that day, and then add it to obtain the local latitude value. Because Polaris is not strictly at the North Pole, there is an error of about half a degree in measuring the latitude of Polaris elevation. In addition, after obtaining the direction of due north, the time when the sun passes due south is recorded, because Beijing time uses the time of 120 degrees east longitude, and the longitude can be obtained by using the time difference between the recorded time and 12 o'clock.

There is also a measurement report for high school students to take a look at:

The first step is to erect a stick. The second step is to find the direction of due south and north. The third step is to look at the time when the shadow of the stick is due north.

If you can't find the direction due north, then observe the shortest shadow of the stick. The shadow of the stick is due north (or the shortest shadow) must be 12 o'clock local time in the school location, and then look at the clock time (in China, all clocks are Beijing time, local time in the 8th East District) and calculate how much the clock time differs from local time. Let's say the clock time is 13 o'clock.

This means that your local area is one hour behind Beijing time. Your longitude is 105 east longitude.

The immediacy problem mainly examines the height of the sun at noon. From the conditions in the question, we know that March 21 is the vernal equinox, then the latitude of the direct point of the sun is 0 degrees, and then the shadow length and the rod length are equal to form an isosceles right triangle, and the noon sun height is 45 degrees.

Then set the formula: h=90 degrees—|Latitude of a place (a) Latitude of a point where the sun shines directly (b)|It can be concluded that the latitude of the place is 45 degrees north latitude.

According to the shortest time of shadow length (i.e., 12 noon local time), Beijing time is 11:44 a.m., and the local longitude can be calculated as 124 degrees east longitude.

Combined with the longitude and latitude conditions, it is concluded that the school is located in Jilin Province.

There are no figures!

The answer is obtained from "the shadow length is the shortest of the day", and the local local time is 12:00, and the Beijing time in the question is 11:44 on March 21, that is, the local time is 16 minutes earlier than Beijing time, according to the geospatial positioning, to exclude the alternative answers, b Xinjiang (73°40 e 96°18 e, 34°25 n 48°10 n), c Yunnan (about 90e-105e), the rest of a and d can be selected, and the weight is said " The shadow length (s) and the rod length (h) are equal" that is, the angle is 45°, the date is, the vernal equinox, the sun is directly shining at the equator, and then look at the latitude of Shandong and Jilin, Shandong is about 34n-37n, left and right, Jilin is between 41n-46n, and the angle of the shadow length is the latitude of the rod length, that is, the answer is Jilin, d.

The content is a bit much, so it is recommended to check the reference book.

The local pole shadow is the most clever and short, then the local is noon, that is, 12:00, because Beijing time is 11:56, filial piety 60 15 = 4 (15 ° 1 hour 1 ° 4 minutes to answer the clock) so Beijing time is 4 minutes later than this, so this place is 1 ° east of Beijing, that is, the longitude of this place:

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The shortest shadow of the sun means that the time is 12 noon local time, and the Beijing time chain is 4 minutes faster than the local time, and the east time is faster, and the place is on the west side of the 120-degree meridian, so it should be reduced. And four minutes is exactly 1 degree difference, so the shed branch is 120 minus 1 The result is 119 degrees east longitude.

(1) Benchmarks, rulers, ropes, clocks and watches (2) arctan (3) 120. 12-t)× 15 。Hours (4)90. arctan

Question 1: A Question 2: D

Question 1: According to the shortest shadow measured at 11 44 Beijing time, the longitude position of the place can be calculated, and according to the equal length of the pole shadow and pole on March 21, it can be seen that the altitude angle of the local sun is 45° when the sun hits the equator directly, so the local geographical latitude can be calculated, so item A is correct.

Question 2: At 11 44 minutes Beijing time, the local time is 12 o'clock, and the local longitude can be calculated to be 124°E. The correct answer is D.

<> steps: On a sunny morning, insert the thin rod vertically on the ground (o-point), and draw a circle on the ground with a radius slightly smaller than the length of the rod shadow at that time, with the "interpolation point" as the center of the circle.

When the shadow end of the rod falls on the circumference, mark a; In the afternoon, when the shadow end of the rod falls again on the circumference, mark b.

Connect AB, find its center C, and connect OC.

On the second day, when the rod shadow coincides with the OC (12 o'clock local time), the time is recorded by reading the meter (Beijing time, or local district time).

Using the above data, the local longitude is calculated.

Combined with the diagram, it is known that the general shadow is in the north, so it is determined that the school teaching building is directly west of the flagpole; Combine options

Therefore, c