How is it possible to lie without harm on a bed of nails?

We know that pressure is a force divided by area over which the force is exerted. When a person lies on a bed of nails, the force equal to the weight of that person acts on the surface of the bed containing nails. Here, the weight is distributed over hundreds of nails that makes the pressure at the tip of each nail safely small. If the same person stands on his feet, he will surely feel the sharpness of the nails because in this case the area of  contact is very small. So, the weight will be distributed over a few nails and hence the pressure will be relatively large.   

What is the reason of cooler air coming out of a bursting tire?

We know from the ideal gas law that pressure increases proportionally with the increase of temperature when volume is held constant for a given mass. As the air inside the tire is in compressed state, the temperature inside the tire is high. When the tire bursts, air inside the tire comes out very fast causing a sudden expansion and decrease in temperature. Therefore, the air is relatively cooler than the surroundings. Blowout of tire occurs when the location of tearing of the tire is incapable of containing the pressurized air and the escaping air causes further tear of the tire.

How glass is broken with sound?

When any object composed of an elastic material is disturbed, it will vibrate at its own special set of frequencies, which together form its special sound.The frequency is the natural frequency of that object. The tendency of one object to force another object into vibrational motion is called forced vibration. If an unmounted tuning fork is struck, the sound it makes is faint. Hold the base of the fork on a table top, and the sound is relatively loud. This is because the table is forced to vibrate, and its larger surface sets more air in motion. The table top becomes a sounding board, and can be forced into vibration with forks of various frequencies. When the frequency of forced vibrations on an object matches the object's natural frequency, a dramatic increase in amplitude occurs. This phenomenon is known as resonance. A glass has a natural frequency. Now if the pitch of the sound creating forced vibration match the resonant frequency of glass the vibrating air will cause the glass vibrating too. If this occur with sufficient volume, right frequency and high enough amplitude, this will cause exceed the strength of the glass to resist the vibrations. When the sound gets too loud for the glass to vibrate, it breaks the glass.