Which is the more reasonable measurement of the distance between the tracks on a DVD:
7.4 ⋅ 10−4 mm or 7.4 ⋅ 104 mm? Justify your answer.

Question

Which is the more reasonable measurement of the distance between the tracks on a DVD: 
7.4 ⋅ 10−4 mm or 7.4 ⋅ 104 mm? Justify your answer.

misssmartiez · Answer

By the way, its 10^-4 and 10^4

misssmartiez · Answer

I believe it is 10^-4, but why?

misssmartiez · Answer

@phi

phi · Answer

which is bigger  10^-4  or 10^4 ?

misssmartiez · Answer

10^4 is bigger.

misssmartiez · Answer

I believe the answer is 10^-4, since tracks on a dvd can't stretch out long?

(What are tracks..? Recordings?)

phi · Answer

next, any idea how big a millimeter is ?
I think it's like about the thickness of a line on a piece of paper (or maybe a thick hair)

CD's are written as circular "tracks"  by a laser. They are very hard to see

phi · Answer

Have you ever seen a phonograph record?  Thomas Edison invented them, and they had "grooves" that a needle rode in.  CD's used the same idea, but much thinner tracks, and a laser "reads" them.

phi · Answer

anyway,  7.4 ⋅ 10−4 mm  makes sense (this a a very thin track) compared to
7.4 ⋅ 10^4 mm  which is 7.4 * 10^3 cm  or 7.4 * 10 meters
or 74 meters  (which is almost 100 yards, the size of a football field)

misssmartiez · Answer

Alright, thanks :)

phi · Answer

They should redo this question, because I think CD's are becoming obsolete, and some people don't know about them.

misssmartiez · Answer

@phi, can you help me with another question?