Sound waves are longitudinal waves. They need a medium to travel through. They cause particles of the medium to vibrate parallel to the direction of wave travel. Sound cannot travel through a vacuum because there are no particles to carry the vibrations.

One of the prime reasons you can hear your downstairs neighbor is because the floor is too thin. If your landlord allows it, thicken the floor using carpets. If carpets are against the rules, consider investing in thick area rugs. They will muffle the sounds, and you have a peaceful life.

10 Ways to Annoy Your Upstairs Neighbors Into Being Quieter

1. Cook Something Smelly.
2. Prank Call Them.
3. Oil up Their Doorknob.
4. Sign Them up for Junk Mail.
5. Knock On Their Door at Odd Hours.
6. Put Speakers up Against the Ceilings.
7. Hit the Ceiling With a Cane or a Broom.
8. Tap the Radiator Pipes With a Metal Spoon.

Sounds can travel at approximately 6000 metres per second in some solids and at a quarter of this speed in water. This is because the molecules of solids are more tightly packed together than in liquids and those in liquids are more tightly packed than in gases.

We can hear sounds around corners but we cannot see around corners; yet both sound and light are waves. Explain the difference. The bending of waves around corners or obstacles is called diffraction (see 34-1). Diffraction is most prominent when the size of the obstacle is on the order of the size of the wavelength.

Diffraction: the bending of waves around small* obstacles and the spreading out of waves beyond small* openings. The fact that you can hear sounds around corners and around barriers involves both diffraction and reflection of sound. Diffraction in such cases helps the sound to “bend around” the obstacles.

Light goes in straight lines, if not being reflected by a mirror or bendt by a prism. Due to this, we can not see around corners because then the light would have to bend around corners. And light does not do that.

Yes, light can bend around corners. In fact, light always bends around corners to some extent. This is a basic property of light and all other waves.

The main reason that we can hear sounds around corners, but not see around corners, is diffraction. Sound waves have very long wavelengths when compared to light waves, which makes diffraction effects much more obvious.

What are two ways that you could direct a light wave around a corner? interacting with other objects and internal diffraction.

Any physics student knows that light travels in a straight line. When light rays pass from air into water, for instance, they take a sharp turn; that’s why a stick dipped in a pond appears to tilt toward the surface. Out in space, light rays passing near very massive objects such as stars are seen to travel in curves.

The ‘colour’ of an object is the wavelengths of light that it reflects. This is determined by the arrangement of electrons in the atoms of that substance that will absorb and re-emit photons of particular energies according to complicated quantum laws.

In general, the more light an object absorbs, the more heat absorbed since light is energy. Black absorbs the most heat. A black object absorbs all wavelengths of light and reflects none. Objects that are white, on the other hand, reflect all wavelengths of light and therefore absorb the least heat.

Anything that reflects a color will look that color. White, gray, and black are not colors, though: white reflects all colors, black absorbs all colors, and gray reflects some and absorbs some of all colors. Any light that is absorbed, of any color, becomes heat.

Fabrics with darker or more intense colors had better UV protection, the researchers say, and yellow shades offered the least. The scientists say clothing manufacturers could use information from the study to design clothing that provides better protection against harmful rays.

Different pigments are used in different concentrations so will persist longer. Black is likely to last the longest simply due to the concentration of dye (although it will stop looking “black” quite quickly). Yellow is normally the least dense.

Dye colors with shorter wavelengths have more energy. These colors have a greater tendency to resist fading. They also have more energy and don’t absorb as much UV light. Purple and blue will fade the least in sunlight.

The brown dyes always have the longest staying power. In fact, brown is a most common natural hair color, which pierces the hair more extremely than other hair dyes.

Synthetic fabric tends to hold dye better than natural fabrics such as 100 percent cotton fabric. Thus, cotton fabric fades faster. Cotton fabric is woven from white fibers extracted from the cotton plant.