Kevin Joel

Ok I'm trying to make a traffic light out of 555 timers, however the charging time towards 1/3 Vcc is throwing my caculations off.... so how do you make it so that the capacitor will never go below that value so i dont have to worry about those things...

I am using the 555 timer as a astable multivibrator in conjunction with other 555 timers. The output of the main 555 timer is used as the source for the next 555 timers. Because it is a design of a traffic light, the up times are very long so charging towards 1/3 Vcc is very disruptive...

In an experiment, our group decided to measure the specific heat of two metals. We did this by heating the metals and putting them into a calorimeter filled with water. To heat the metals, we boiled some water, and then submerged the metals there until they reach their maximum temperature. However, their temperatures were only coming up until about 80 degrees C( this is different for the two metals, which are brass and aluminum). The thing is, the water was already boiling so it was at 100 deg. So my question is how was it that they only reached 80 deg. and just stay there? Were they already at thermal equilibrium or would it just take a long time(like more than half an hour) to do it?

In an experiment, our group decided to measure the specific heat of two metals. We did this by heating the metals and putting them into a calorimeter filled with water. To heat the metals, we boiled some water, and then submerged the metals there until they reach their maximum temperature. However, their temperatures were only coming up until about 80 degrees C( this is different for the two metals, which are brass and aluminum). The thing is, the water was already boiling so it was at 100 deg. So my question is how was it that they only reached 80 deg. and just stay there? Were they already at thermal equilibrium or would it just take a long time(like more than half an hour) to do it?

We were doing an experiment in class, where we pumped steam into tubes, to test the effects of thermal expansion. The problem is that the temperature of the tubes quickly increased up to 80 deg. C; afterwards, the increase in temp. became really slow, like 2 deg. per minute. btw, we were using a thermistor to check for the temp.

Anyways, I remember reading that perspiration cools our body using evaporization, so couldn't condensed water inside the tube cause it to absorb the heat instead of the metal taking it.( note that the steam would've turned into water when it released heat towards the tubes). However, we did tilt the tubes so that the water would drain out but could this still be substantial enough to retard the heating process??? If so,, what's the phenomenon called?