Distance of 1 pc(parsec)
Parallax When an object is close to me, you can use a ruler to measure the distance. But, it isn’t easy to measure when the object is away from me. In this case, how can you … more
Distance
Solar System
Solar System All the orb bodies that revolve around the sun and their space are called the solar system. The celestial bodies that make up the solar system include the eight planets revolving around the sun … more
Earth’s gravity
Gravity Gravity is the force that is attracted between all objects with mass. According to Newton, an object with mass attracts each other with force proportional to the two objects’ mass and inversely proportional to the … more
Range and Intensity of the Gravity
Gravity Gravity is the force that is attracted between all objects with mass. According to Newton, an object with mass attracts each other with force proportional to the two objects’ mass and inversely proportional to the … more
Minimal force required for the lever
Lever A lever is a tool that transmits force using a rod. With a lever, you can work with it having little force. The length of the lever can adjust the minimum force required to move … more
‘Work’ in science
‘Work’ in science ‘Work’ in science and ‘work’ in everyday life is a little different. In science, ‘work’ is to apply a force to an object and move it in the force’s direction. In the following … more
Apparent Magnitude, Absolute Magnitude, and Distance to Stars
Star brightness and apparent magnitude Hipparchus of ancient Greece distinguished the stars in the night sky according to their brightness. He classified the brightest star as ‘magnitude 1’ and the darkest star as ‘magnitude 6.’ The … more
3D Location of the Ursa Minor(Polaris)
Constellations and distance to stars If you look at the sky where there is no light on a clear night, there are so many stars that can not count. Thousands of years ago, the ancients linked … more
Why does the moon seem to follow me?
Is the moon really following me? How can you explain that the moon looks follow I? The moon doesn’t follow me. For example, if I go forward with a car, the landscape seems to move backward. … more
Pulleys with Many Wire
Movable Pulley Movable pulleys can move axes, unlike fixed pulleys. Movable pulleys have the advantage of being able to move with less force. But, the distance that I have to move is longer than the fixed … more
Pulleys with One Wire
Movable Pulley Movable pulleys can move axes, unlike fixed pulleys. Movable pulleys have the advantage of being able to move with less force. But, the distance that I have to move is longer than the fixed … more
Parallax of Eyes
Parallax When an object is close to me, you can use a ruler to measure the distance. But, it isn’t easy to measure when the object is away from me. In this case, how can you … more