aliasgherman

This is a very good thread indeed. I would like to point out that Fenyman can get 94, because BOTH michelson and cherenkov have got the same value(109).

Kind of a very basic question, but I am not basically a physicist. A bucket with two holes on its sides is filled with water. If the bucket is allowed to free fall from a tower, will the water fall through the holes OR the water will not fall OR the water will spill from the top of the bucket ????

Me and one of my friend had done some experiments related to pyrochemistry sometimes ago. They were aimed at Rocket flights. Later it was told to us that we cannot construct a rocket model as it is illegal. Now we had a fair amount of Black Powder which we would have been unable to use for rocketery. What we did was that we used small cars as a model. Attached a steel container containing the black powder. A resistor (for triggering the powder by passing very high current through it), 9V battery, and 555 timer circuit for 3 seconds delay before launch. The container and the car body was separated by using some insulations between them and airgap as well. Then the race began. (Both me and my friend made a car each with own design). When 555 timer expired it connected the 9V terminal to the resistor making a flow of 500mA through it. The resistor went hot and after sometime triggered the feul. After that the car started to move. On the other hand my friend's car started as soon the whistle was blown. (He had not used any delay timers). His car was pretty fast as compared to mine. Within sometime my car also gained some speed, and my friend's car was almost on fire as the insulation between the container and car was not sufficient. Near the finish line my friend's car was a total mess and fully blown up. My car on the other hand was experiencing bumps (due to small nosel of the container the powder was not burning efficiently). Final Results My friend's car reached the end line but was totally wasted. My car never make it to the finish as the container exploded due to a small nosel. If you have reached here then you must be very patient reader The purpose of sharing this information is that we feel that a competition like this is really great fun. Any replies are welcome.

I was wondering if anyone could tell me the list of chemicals used in the process of through hole plating. I have heard that there are almost 7 chemicals used for this process. Something called activator etc. I would be very thankful for this information, as I usually have to make PCBs and our fabricator has no setup for through hole plating, hence the PCBs are only single sided.