A question for the physicists here...

[Beatle_ki_wapsi]

A CD has a small radius of 25 mm and a larger radius of 58mm. The tracks on the CD are 0.5micro meter thick and 1.6 micrometer apart.
Q1) How many tracks are there?
Q2) Prove that the total length of the tracks is 5km.

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[Beatle_ki_wapsi]

The only answer I could get for the second part is about 2.5 km....

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[Ghoncho]

Interesting question. I am working on it already should post the answer in a little bit. Hold on. I cant fogure out how many meter is a micrometer

[Beatle_ki_wapsi]

1 micrometer = 10 e-6

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[who---me]

array mian "e" kahan say aa gia?

[hmcq]

1 um = 1 x 10^-6 m

That is there are 1 million micrometers in 1 meter

[hmcq]

so was anyone able to compute the lenght?

I vagely remember getting 2.5 Km as well but I did not complete the calculation.

Please post here if you have been able to get the result

[Beatle_ki_wapsi]

Wasn't anyone able to get an answer?

BTW, here is another one which was in my finals:
You have to investigate how the force of friction acts on different brands of shoes.
you are provided with a string attached to the shoe.
Q1) Give three essential pieces of apparatus which would be required to carry out the investigation and state why they are important.
Q2) How would you carry out the investigation?
Q3) Give two reasons why the results of this investigations cannot be applied to real life running?


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