Join as a Pro. Houzz TV. Houzz Research. Shop Featured Holiday Categories. Home Decor. Holiday Decor. Christmas Trees. Holiday Lighting. My second guess has to do with angular momentum. If you consider the piece while it is still connected to the CD, that piece is rotating it goes from oriented up to down and back to up as the CD spins.
If the piece has angular momentum before the break, it should still have angular momentum after the break. After the break, this force is no longer there. What do objects without forces on them do? Moving in a straight line means the object has constant velocity. But wait! The piece does accelerate after the break. Yes, I think this is due to air resistance just a guess.
If a piece broke of in such a manner that it shot straight up, would you be able to see a change in speed due to the gravitational force? If so, could you use this acceleration to check that the frame rate is correct? If not, why not? If there is indeed a significant air resistance on the piece of CD, can you detect this force on other pieces too? Should a smaller piece have a higher or lower acceleration due to air resistance? Estimate the mass of a piece based on the size to get a ball park figure for the acceleration due to air resistance.
What is the breaking strength of a CD? You might want to assume the CD is polycarbonate plastic to get a value of the tensile strength.
Is this why the CD broke? Have you ever wonder how compact discs work? Understanding the CD: Material " ". Understanding the CD: The Spiral " ". Understanding the CD: Bumps " ". CD Player Components " ". A drive motor spins the disc. This drive motor is precisely controlled to rotate between and rpm depending on which track is being read. A laser and a lens system focus in on and read the bumps.
A tracking mechanism moves the laser assembly so that the laser's beam can follow the spiral track. The tracking system has to be able to move the laser at micron resolutions. CD Encoding Issues " ". Because the laser is tracking the spiral of data using the bumps, there cannot be extended gaps where there are no bumps in the data track. To solve this problem, data is encoded using EFM eight-fourteen modulation. Because the laser wants to be able to move between songs, data needs to be encoded into the music telling the drive "where it is" on the disc.
This problem is solved using what is known as subcode data. Subcode data can encode the absolute and relative position of the laser in the track, and can also encode such things as song titles. Because the laser may misread a bump, there need to be error-correcting codes to handle single-bit errors.
To solve this problem, extra data bits are added that allow the drive to detect single-bit errors and correct them. Because a scratch or a speck on the CD might cause a whole packet of bytes to be misread known as a burst error , the drive needs to be able to recover from such an event. This problem is solved by actually interleaving the data on the disc, so that it is stored non-sequentially around one of the disc's circuits. The drive actually reads data one revolution at a time, and un-interleaves the data in order to play it.
If a few bytes are misread in music, the worst thing that can happen is a little fuzz during playback. When data is stored on a CD, however, any data error is catastrophic. CD Data Formats There are several different formats used to store data on a CD, some widely used and some long-forgotten.
Any attempts to peel the label off could cause damage to the lacquer and metal layers in CDs. DVDs are different; peeling a label off a DVD would not have the same adverse affect because the metal layer is not near the surface. Still, removing a label, or any portion thereof, from the surface of a disc can cause an imbalance in the spin of the disc in the disc drive, making the disc unreadable.
DVDs are more susceptible to reading problems from minor imbalances than are CDs. To ensure the long-term availability of information on a disc that already has an adhesive label, the information on the disc should be copied to, and stored on, a disc without such a label.
Adhesive labels may be well suited for short-term disc usage less than five years , and can even add a layer of protection from scratches and other potentially harmful contact.
On the other hand, such labels are vulnerable to adverse environmental conditions: they can dry out or absorb moisture, and they can be affected by heat or cold even more than the disc itself. Such conditions may cause the label to delaminate. Disc manufacturers advise against using adhesive labels because they can create unbalanced disc spin, resulting in premature wear of the drive.
If a label is used, it should be manufactured for use on CDs or DVDs, and an appropriate disc label applicator tool should be used to affix the label. The label applicator tool should center the label on the disc so as to maintain the disc balance as much as possible.
Inkjet printing and thermal transfer printing are commonly used for labeling the surfaces of CD-R discs. Each involves a different technology to place inks on the printing surface of the disc; few inkjet-printable and thermal printable CD-Rs are interchangeable. The printable area on a DVD disc depends on whether the disc is single- or double-sided. Because ink affects the flatness and balance of a disc, full surface printing may not be the best choice since the ink may not be uniformly distributed over the disc surface.
Nonetheless, if you choose to print labels on your discs, full surface printing is better than partial surface printing. The pits are produced on the label side without having a printable surface , creating a mirrored, holograph-like pattern on the metal layer that becomes the label.
Because no ink is used, the flatness and balance of the disc are not compromised. If a DVD disc has data on both sides double-sided , neither printing nor pit art may be used in the data area of the disc. Only the area of the mirror band and the area between the mirror band and center hole may be printed on or marked.
Thermal Printing In thermal transfer printers, a print head that contains resistive elements in a linear array heats ink-coated films ribbons. The ink is heated, causing it to melt and adhere to the printing surface. Specially formulated materials are used for the printable surface of the disc to enhance ink transfer efficiency and adhesion.
Only specially designed thermal printers-not thermal printers designed to print on paper-can be used to print directly on the surface of thermal printable CD-R discs.
Inkjet Printing In inkjet printers, inks are sprayed, via droplets of an ink solution, onto a specially designed printable surface material on the disc. This surface is designed to hold the ink droplets in place while absorbing the liquid components of the ink.
That ink cannot contain any chemically active components that can affect the disc after the curing process or abrasive particles in the ink pigments that can damage the protective layer of CDs. CDs and DVDs do not wear from friction as vinyl records or tapes do. There is no physical contact with the disc in the area that the laser uses. In theory, it is possible for the disc to be read so many times that the cumulative effect of the laser light can eventually affect the polycarbonate.
There is, however, no record of such discs having been played a sufficient number of times to incur damage from laser light.
Accordingly, it is felt that any effects of the light on ROM discs is negligible. It is assumed, in fact, that the disc would likely fail much earlier from some other condition than from the effects of laser light. R discs : In theory, R discs should have a limited number of read times several thousand because of the cumulative effect on the data layer from the laser light.
As with ROM discs, the polycarbonate may also eventually be affected, but there is no recorded evidence of ill effects of laser light, so such effects are deemed negligible. The reading functionality of the disc should continue for a limited number of read times after each writing. While the maximum number of read times possible after writing is unknown, it may become fewer after each successive writing. CLIR is an independent, nonprofit organization that forges strategies to enhance research, teaching, and learning environments in collaboration with libraries, cultural institutions, and communities of higher learning.
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