Let's make a sundial, compass, and my globe
One of the regular and natural movements is the movement of celestial bodies. We will make a sundial using it. Grasp the movement of the sun without thinking too much about correction.
Experiment 1: Let's make a sundial (for Tokyo and its surroundings)
you need : Bamboo string, drawing paper, ruler, compass
This time, I will talk about sundial. I think you've seen it somewhere once. Although it is simple, it is a wonderful teaching material for dealing with the rotation of the earth. It's easy to make.
Referred to as the rotation to one rotation from west to east around the earth's axis in one day is Earth itself. This time we will use this rotation.
As we live above Japan, we cannot feel that the earth is spinning, but it is always moving eastward at the same speed. The sun moves westward, as if the train goes forward and the building seen through the window goes behind. This movement is exactly 15 degrees per hour. After that, I will make this shadow appear on the dial.
The simplest one is a disk with a bamboo skewer as shown in the picture above. This is so that the earth's axis and the bamboo skewer are parallel. Then, it becomes like the figure in the middle, and the shadow is reflected on the dial as if the sun is rotating around the bamboo skewer. However, the angle between the bamboo skewer and the disk tends to shift, so we will reinforce it a little more. If you allow the dial to rotate, it will be easier to make corrections according to the seasonal changes in the south-central time of the place.
Paste the dial on the construction paper. In Tokyo, 11:46 is the time in the south (varies depending on the season), so paste it so that it is directly below. A summer dial is also attached to the front side. Fix the construction paper at 55 ° on the PS board.
When you stab a bamboo skewer, the bamboo skewer will be tilted at 35 °, which is the same as the earth's axis. In winter, the shadow is reflected on the inner dial, and in summer, the shadow of the bamboo skewer indicates the time on the outer dial. Please download the dial from the PDF file below.
About sundial error
Difference by longitude Difference by north latitude Magnetic north and true north of compass
Latitude and longitude vary from place to place. Find out the seasonal culmination time of the national observatory. Then, find the difference in longitude between the city you live in and the observatory. There is a difference of 4 minutes for each difference. Also, the angle of the bamboo skewers should be the same as the north latitude.
Experiment 2: Let's make a compass
you need : straw, steel wool, aluminum foil
There are many ways to make a compass, but there aren't many that I think are the best. If you can get a ferrite magnet, it is easiest to attach a thread and hang it as shown in the picture above. The pictures below show the one with a bar magnet floating from the left, the one with a donut magnet sandwiched between styrol balls, the one with a needle hung, the one with a steel can cut and placed on the drawing, all of which have advantages and disadvantages, but the steel can The one that is cut out has the disadvantage that it takes time and effort, but it is very good. How to make it is put on the PDF file below. Iron, cobalt and nickel are magnetized. If you place these so that they can move easily, they point to north and south.
This time, we will make a compass from straw, aluminum foil, and steel wool, which are easily available.
Prepare a straw, aluminum foil, and steel wool cut to about 3 cm. Wrap steel wool in aluminum and push it into the straw. Cover both ends of the straw and magnetize it with a magnet. Float on water and you're done. When blocking the straw, use a pair of needle-nose pliers and heat it with fire. In winter, static electricity is strong and it may stick to the container.
The north pointed by the compass is exactly off the north. In Tokyo, it is about 7 degrees west. This is called declination. For more information, please contact the national map-making agency.
Experiment 3: Let's make my globe
you need : Ping-pong ball
All you have to do is print the image on a sticker and stick it on a ping-pong ball, but having your own will increase your interest. This can be downloaded from the website of Professor Sato of Numazu National College of Technology.
Also, if you want to make an original globe from a world map, please go to the site called BeagleGraph. If you specify as below, you can create a development map of the original globe.
You can also print it on paper as a polyhedron and make it as a globe. Go to the site called globe.exe and download the software. The photo below is made with octahedron. With this, it can be assembled even in the lower grades of elementary school and does not require ping-pong balls.
Having your own laboratory equipment, not just earth science materials, greatly stimulates the interests of children and students. Both are not very expensive, so please take a look.