«Imagination is more important than knowledge. Indeed, knowledge is limited, while the imagination covers the whole world, stimulating progress, creating evolution", - Albert Einstein.
The knowledge that we gain in physics lessons lays the foundation for all the other amazing things that we continue to learn. But science definitely does not end in high school, and as soon as you take your education to the next level, things become really interesting.
The universe is a crazy place. With the help of physics, we learned a lot about its mysterious nature, but we still have a long way to go! Let's get started. We recommend you a list of 10 interesting facts about physics for children in grade 7: curious physical phenomena and properties.
10. Distilled water is a dielectric
"Water capacitors", where water is a dielectric, are commonly used in very high voltage switching systems.
For example, high power nitrogen lasers typically use water capacitors as a component of energy storage. When used in these applications, a resin deionizer is used to drastically reduce the conductivity of water.
The great advantage of using water as a dielectric in these high-voltage applications is that it is self-healing, unlike solid Dielectric. Thus, deionized water can and is used as a dielectric.
9. Glass is not considered solid because it is a liquid
It is sometimes said that glass in very old churches is thicker from below than from above, because glass - liquid, and therefore for several centuries it flowed to the bottom. It is not true.
In medieval times, glass panels were often made using the corona glass method. A piece of molten glass was rolled, blown, expanded, flattened, and finally rotated into a disk, and then cut into glass. The sheets were thicker towards the edge of the disc and were usually set so that the heavier side was below.
To answer the question “Is the glass liquid or solid? ” we must understand its thermodynamic and material properties. Many solids have a crystalline structure on a microscopic scale.
The molecules are arranged in the correct lattice. When a solid body heats up, the molecules oscillate around their position in the lattice until the crystal breaks at the melting point and the molecules begin to flow.
There is a clear difference between the solid and liquid state, which is separated by a first order phase transition, that is, an intermittent change in material properties, such as density. Freezing is marked by the release of heat, known as melting heat.
8. If hydrogen burns in air, water is formed.
Hydrogen burns in oxygen to form water. The flame is almost colorless. Mixtures of hydrogen and oxygen (or hydrogen and air) can be explosive when two gases are present in a certain ratio, so hydrogen should be handled very carefully.
7. Light has weight but no mass
If there was a simple answer, how much light weighs, we would all know that. In fact, Einstein proved that energy and mass can be one and the same - all energy has some form of mass.
Light may not have a resting (or invariant) mass that describes the weight of the object. But due to Einstein’s theory (and the fact that light behaves as if it has mass, because it is subject to gravity), we can say that mass and energy exist together. In this case, we would call it relativistic mass - the mass when the object is in motion, and not at rest. Thus, the "weight" that you measure is a form of energy.
6. Pluto has not circled the sun since its discovery.
Pluto was discovered on February 18, 1930. A dwarf planet needs 248.09 Earth years to complete one orbit around the Sun. Simple arithmetic, and we find that Pluto will complete its first full revolution since its discovery on March 23, 2178.
5. Most of the water is in the sun.
According to scientist Charles Choi, when the solar wind blows on oxygen-rich stones, a combination of hydrogen and oxygen can lead to the formation of water. This process can develop anywhere with the right types of stones, from the surface of the moon to a lone particle of interplanetary dust.
Thus, part of the water that creates the conditions for the emergence of life on Earth may have been born from the Sun.
4. Liquid, gaseous, and solids always expand when heated.
When heat is added to a substance, molecules and atoms vibrate faster. When atoms vibrate faster, the space between the atoms increases.
The movement and distance between particles determines the state of matter. The end result of an increase in molecular motion is that the object expands and takes up more space.
However, the mass of the object remains the same. Solids, liquids and gases expand when heat is added. When heat leaves all substances, molecules vibrate more slowly. Atoms can come close, which leads to compression of the substance. Again, the mass has not changed.
3. Sound in air and in water travels at different speeds
Sound travels at different speeds depending on what it goes through. Of the three media (gas, liquid, and solid), sound waves travel through gases more slowly, faster through liquids, and faster through solids. Temperature also affects the speed of sound.
The speed of sound depends on the properties of the medium through which it passes. When we look at the properties of a gas, we see that only when the molecules collide with each other, rarefaction of the sound wave can occur. Thus, it makes sense to say that the speed of sound has the same order of magnitude as the average molecular velocity between collisions.
In gas, it is especially important to know the temperature. This is due to the fact that at lower temperatures the molecules collide more often, which gives the sound wave more chances to move quickly.
When freezing (0 ° Celsius), sound travels through the air at a speed of 331 meters per second (about 740 miles per hour). But at 20 ° C room temperature, the sound travels at a speed of 343 meters per second (767 miles per hour).
Sound travels faster in liquids than in gases because molecules are denser packed. In fresh water, sound waves travel at a speed of 1482 meters per second (about 3315 miles per hour). It is more than 4 times faster than in the air!
Several ocean-dwelling animals rely on sound waves to communicate with other animals and find food and obstacles. The reason they can effectively use this communication method over long distances is because sound travels much faster in water.
2. Clean snow melts more slowly than dirty snow
Dirty snow usually melts faster than fresh because it absorbs more energy from the sun., and this is not only a problem in sooty, sandy cities.
With the exception of some mountains and high plateaus, snow cover naturally recedes from the Earth's surface in spring and early summer. Dust on top of this snow greatly speeds up the process.
1. The whip is considered the first device that overcame the sound barrier
The sound barrier may have been first overcome by living things about 150 million years ago. Some paleobiologists report that, based on computer models of their biomechanical capabilities, some long-tailed dinosaurs, such as the Brontosaurus, Apatosaurus and Diplodocus, may have snapped their tail at supersonic speeds, creating a crackling sound. This conclusion is theoretical and is disputed by others in this area.
Meteors entering the Earth’s atmosphere usually, if not always, fall faster than sound. However, the first device to break the sound barrier is a regular whip or whip.. The end of the whip moves faster than the speed of sound, creating a distinctive sound.