Wednesday, December 06, 2006

Longawaited replies

This is to reply to two posts I found close to my heart.
Going by chronological order.

1. Mechanical vacuums.

This reply will be a bit technical but do excuse me.
Bernoulli's principle as far as I understand is a clever restatement of the law of coservation of energy. Hence I will proceed with conservation of energy itself to check the feasibility of a mechanical vacuum.

Let us consider that the vacuum has a circular cross section nozzle with a radius of 1 cm.
A standard vacuum generates 20kPa pressure difference between outside and inside.
By Bernoulli's principle,
(1/2)*d*v^2 = (P2-P1)
Thus, v = 180 m/sec
Now, Power = (energy)/time = ((1/2)*m*v^2)/t = (1/2) *d*A*v^3
= (1/2)*(pi*(o.o1^2))*1.2*180^3 = 1100 watts
Assuming a modest efficiency for the mechanics at 50%.
Total input power = 2200 watts.
Power output of a human being working hard physically = 500 watts.
Hence I would tend to believe this is not feasible.

NOTES :
d= 1.2 kg/ m^3......density of dry air.
Standard data such as pressure diff. in vacuums and output of a human courtesy Wikipedia.

2. Mission to the moon

Construction of moon bases is not as easy as it seems.
NASA's press release though impressive, I believe is over optimistic.
The ISS which is one thirtieth the distance to the moon remains incomplete inspite of regular shuttle flight and the co-operation of 16 countries. In this context it is highly improbable that a habitable base on the moon will be built within the next 50 yrs. Chandrayan has a more modest completion date i.e. by 2008.

More importantly if robots are to be sent than a moon base itself is irrelevant. The robot will survive of solar power and will explore when it is fully charged. Why would we need a moon base.

- By Zero.

P.S.
The last post on the moon issue was by me. Didn't realize my name wouldn't show up.

1 comment:

Unknown said...

Aha.. you are missing a point... things hanging in sky are always difficult to manage...how much time did Nasa took to put robos on Mars... putting something on some other extra terrestrial place and managing some thing hanging in space are two different propositions. I think making a moon base is not that big a trouble, the more troublesome thing would be visiting it. You must also read something which is not being stated...what would I gain from it... tourism.
Chandrayana is a very nice concept and 2 years for which it would be rotating around moon would certainly e a good and healthy time. But what I want is that India should drop the idea to put man on moon. One more reason to support my point is that... the first man will most likely be a pilot and not a scientist. This is one more reason that I would really love to put robo on moon.