How to measure the diameter of the earth
Here are a few ways to measure the diameter of the Earth: 1. ** Radian measurement method **: The first measurement by the ancient Greek Astronomist Eradossus using sunlight. He found that during the summer solstice, the bottom of the well in Sai City could be directly exposed to the sun, and the upright wooden pole had no shadow. However, in Alexandria City, which was 500 ancient Greek miles away (1 ancient Greek mile was about 158.5 meters), the upright wooden pole deviated from the vertical direction by 7.2°. He believed that the central angle of the arc between the two places was 7.2°. Based on the distance between the two places and the relationship between the arc length and the central angle, he calculated that the radius of the Earth was about 6310 kilometers, and then obtained the data related to the diameter of the Earth. 2. ** Triangulation Method **: Wallace, who was at the same time as Darwin, proposed to set up two wooden poles with the upper end point distance of A B = 2a and the distance from the horizontal plane of h on the straight canal. In the middle of the two wooden poles, the third wooden pole was erected so that the upper end point C was on the connecting line A B. Since the surface of the earth was curved, the height h1 from point C to the horizontal plane was slightly smaller than h2. Let the Earth's radius be R, UA = OB = R + h, and BG = AB = a. Through the relationship in Rt, one only needed to obtain the length of AB and the height of the two wooden poles to calculate the Earth's radius and thus the diameter. 3. ** Using the sun angle measurement method **: Find a business trip with a longer distance (such as 1000 kilometers). Prepare a ruler to measure the angle of the sun in advance (a flat surface at the bottom with a stick erected on it. When the sun shines, it will draw a shadow on the flat surface). Before he left, he would draw the sun's projection A at a certain point at noon. On the day of his arrival, he would draw the second sun's projection B at the same time. He would ask about the distance between the two places, Y kilometers, measure the angle between the A and B lines, and calculate the diameter of the Earth according to the result of 360Y/X*3.14.
How to measure the diameter of the tree
The diameter at breast height of the clumped trees was measured at a place 1 meter above the ground (referring to the seedlings with higher branches. If the branches were low, the measurement height would also be lower). Because the clumped trees had many trunks and branches, all the branches had to be taken into account when measuring the diameter at breast height. Each branch had to be measured and the data of each branch had to be marked in detail. However, in the measurement of the size of the clumped trees, the diameter at breast height was generally not the main reference. This kind of seedlings mainly looked at the height and crown width, and the diameter at breast height could be used as a supplementary material for measurement. "Life Like a White Birch" is equally exciting. Everyone is welcome to click and read it!
diameter of the earth
The average diameter of the Earth was 12,742.02 kilometers, the diameter of the Earth's equator was 12756 kilometers, and the diameter between the North and South Poles was 12631 kilometers.
What is the diameter of the earth?
The diameter of the Earth is 12742 kilometers.
The diameter of the earth is 12,800 kilometers
The average diameter of the Earth was about 12,742 kilometers, the diameter of the Earth's equator was about 12,756 kilometers, and the diameter between the North and South Poles was about 12,631 kilometers. Therefore, saying that the diameter of the Earth was about 12,800 kilometers was an approximate statement.
How is the diameter of the earth measured?
Here are some ways to measure the diameter of the Earth: 1. ** Radian measurement method **: In 225 B.C., the ancient Greek astronomer Eradossus first used sunlight to measure the radius of the Earth and then the diameter. He found that during the summer solstice, the sun shone directly at the bottom of the well in Sai City, and there was no shadow on the vertical wooden pole. However, in Alexandria City, which was 500 miles away from ancient Greece, the vertical wooden pole deviated from the vertical direction by 7.2°. He believed that the central angle of the arc between the two places was 7.2°. According to the distance between the two places and the relationship between the arc length and the central angle, the radius of the earth could be calculated, and then the diameter could be obtained. It was generally believed that one mile in ancient Greece was about 158.5 meters, so the radius of the Earth was about 6310 kilometers and the diameter was about 12620 kilometers. 2. ** Triangulation Method **: According to the method proposed by Wallace, two wooden poles with the upper end point distance of A B = 2a were erected on the straight canal. The distance from them to the horizontal plane was h. The third wooden pole was erected in the middle of the two wooden poles, so that the upper end point C was on the connecting line A B. Since the surface of the earth was curved, the height h1 from point C to the horizontal plane was slightly smaller than h2. In a circle with the radius of the Earth as R, UA = OB = R+h. Since AOAAB is an isosceles-triangle, so BG = AB = a. In Rt-Boc, the radius of the Earth could be calculated from the length of the A and B and the height of the wooden pole, thus obtaining the diameter. 3. ** Using sun angle measurement method **: - Prepare to measure before and after the business trip (the longer the distance, the better, such as 1000 kilometers). Prepare a ruler to measure the sun's angle in advance (a flat surface below, with a stick erected on it, record the shadow of the stick on the flat surface under the sun's illumination). Before he left, he would draw the sun projection A at a certain point in the afternoon. On the day of his arrival, he would draw the second sun projection B at the same time. The distance between the two places was Y kilometers, and the angle X° between the A and B lines was measured. According to the formula 360Y/X*3.14, the diameter of the Earth could be calculated. - Eratosthenia's method was to observe the shadow of the obelisk in Alexandria Port during the summer solstice. Through the height of the obelisk and the length of the shadow, the angle between the sun and the obelisk was calculated. According to Thales 'parallel angle theorem, this angle was the angle between the two radiuses of the two cities connected to the earth's core. He calculated that the angle was about 7°12 '(about 2% of the circumference of 360°), and then calculated the distance between the two cities (he calculated the distance between the two cities by calculating the number of steps and stride of the camel team and found that the distance between the two cities was 5000 Greek miles. One Greek mile was equal to 157.5 meters), multiplied by 50 times to get the circumference of the Earth, and then calculated the diameter.
What is the diameter and circumference of the earth?
The average diameter of the Earth was 12,742.02 kilometers, the diameter of the equator was 12756 kilometers, the diameter between the North and South Poles was 12631 kilometers, and the circumference of the equator was about 40076 kilometers.
How many kilometers is the diameter of the earth?
The diameter of the Earth was about 12742 kilometers. However, the Earth was an irregular oval with a slightly flat pole and a slightly bulging equator. Its equator had a diameter of about 12756 kilometers, and the diameter between the North and South Poles was about 12631 kilometers.
What is the diameter equivalent to a diameter of 50?
According to the conversion formula between breast diameter and diameter, the diameter of the soil ball = 8 - 10 times the breast diameter. Assuming the relationship of 10 times here, when the breast diameter is 50, the diameter is 50×10 = 500. However, according to the conventional understanding, breast diameter was a representation of diameter. A breast diameter of 50 was equivalent to a diameter of 50. Since the reference materials did not specify the conversion relationship under which circumstances, there were these two possible situations. "Life Like a White Birch" is equally exciting. Everyone is welcome to click and read it!
How to measure the distance between the earth and the sun
The distance between the Earth and the Sun was not measured directly, but calculated indirectly. Here are some of the measurements: ** 1. Venus transit method ** 1. ** Principle Basics ** - Based on the triangular disparity principle. Venus is located on the inner side of the Earth. Every 584 Earth days, the Earth and Venus meet. When Venus is between the Earth and the Sun, Venus can be seen passing in front of the Sun from Earth.(The principle is the same as a solar eclipse, but the Moon's apparent diameter can completely block the Sun. Venus and Earth's orbit is at an angle of 3.4 degrees, so not every encounter will have a transit. It only happens twice every century, and the last two times are eight years apart, such as 2012 and 2004. The next time will be in 2117.) 2. ** Precise calculation ** - If two observers far away from Earth observed the transit of Venus at the same time, the trajectory of Venus on the solar disk would be different for different observation points. The ratio of the observed transit time of Venus to the length (apparent diameter) of the trajectory was proportional. The angle was first calculated through astronomical observations (according to the Pythagoras theorem, combined with the apparent radius of the sun, the transit time of Venus at different points, the orbital angular velocity of Venus, and other factors), and then the distance between Venus and Earth was calculated from the distance between the two observation points. Since Halley knew that the distance between Venus and the Sun was 0.72 times the distance between Earth and the Sun, he could calculate the distance between the Sun and the Earth. In 1761, the result measured by this method was less than 3% different from the modern value. ** 2. Use Venus 'East-West Distance (Venus Distance Method)** - As Venus moved around the sun, the angle between Venus, the sun, and the Earth kept changing. When this angle reached the maximum (Venus's large distance), the line between Earth and Venus was just right to the line between Venus and the Sun. Based on this, the distance between Earth and the Sun was calculated. ** 3. Calculating indirectly through other planets (Venus as an example)** 1. ** Confirm the relative distance relationship ** - Let the distance between the Earth and the Sun be "a". Earth and Venus's orbits were roughly in a perfect circle around the sun and on the same plane. 2. ** Using the maximum extension point ** - Venus has two positions that make the Sun-Venus-Earth angle 90 degrees. These two points are the points of maximum extension of Venus (that is, the point in the sky where Venus appears furthest from the Sun). Through a series of observations of the golden star in the sky, determine its maximum extension point, and measure the angle of the sun and Venus 'maximum extension point in the sky (let the Earth be the apex, and the angle of the straight line pointing in the two directions of the orbit of the sun and Venus be "e"). 3. ** Triangular Function Calculation ** - Using the trigonometriation function, the distance from Earth to Venus =(distance from Earth to Sun)×cos(e). Similarly, the distance from Venus to the Sun =(distance from Earth to Sun)×sin(e). It was known that Venus's maximum extension was about 46 degrees. Based on this, it was inferred that the distance from the Sun to Venus was about 72% of the distance from the Sun to the Earth, thus determining the distance from the Earth to the Sun. A similar method could be used to determine the relative distance between the Sun and Mercury (Mars and the outer planets were more complicated). ** 4. Historical measurement methods ** 1. ** Aristarch's Method (c. 250 B.C.)** - Using the moon's phase to measure the distance between the moon and the sun. During half a month, the three celestial bodies (the sun, the earth, and the moon) should form a right angle. By measuring the angle between the moon and the sun, it was determined that the distance between the earth and the sun was 19 times the distance between the earth and the moon. However, due to the difficulty in determining the center of the sun and the moon and the difficulty in knowing the exact time when the moon was in a semicircle state, the result was inaccurate. 2. ** Huygens 'Method (1653)** - In the triangular region formed by Venus, Earth, and the Sun, he used Venus's phase to find the angle. When Venus was half illuminated by the sun, the three celestial bodies would form a right angle when observed from Earth. The distance between Venus and Earth was determined by guessing the size of Venus, and then the distance to the Sun was measured according to the angle formed by the triangle. However, due to the lack of complete scientific basis, it was not widely accepted. 3. ** Cassini's Method (1672)** - Using the disparity (angle discrepancy) to find the distance to Mars, and at the same time, measure the distance to the Sun. He sent his colleague Jean Richelle to Guyane française and stayed in Paris. They measured the position of Mars relative to the background stars and used the known distance between Paris and Guyane française to triangulate. After measuring the distance to Mars, they could calculate the distance to the Sun. They were praised for their more scientific methods.
Is the diameter or circumference of the tree diameter at breast height?
The diameter at breast height referred to the diameter, which was the diameter of the trunk of the tree 1.3 meters above the ground. "Life Like a White Birch" is equally exciting. Everyone is welcome to click and read it!