I was looking at my cold cup of coffee and wondered how I would calculate how long it took to cool down. Then thought about turning it upside down and how the volume would be displaced with ambient air pretty much instantly, and whether this would be the case if the coffee cup was filled with...
I wanted to know how long it would take (and how I could calculate it) for a volume of air that is cold to equal the ambient air temperature, whether that is by air displacement or by heating due to the higher temperature ambient air it is surrounded by.
What equations would I use to calculate the time taken?
Would this still be the case if the ambient air reservoir was much much larger than the volume?
I have a cube with a volume of 1000m3 at an initial temp of 290K. The bottom side (10m by 10m) is open to the ambient air. I put this cube into a huge fridge and cool the whole volume by 5K. I close the open side by placing a cover on it. This cube has now got a volume of air at a temperature of...
Great, thanks.
It is a bespoke made generator so no specs. Open circuit the pulse is the same shape but about 20% larger in both amplitude and width.
OK but even if it is dissipated into the 9kΩ there would have been a draw from the power supply surely?. So how do we calculate that energy...
Yes your interpretation is correct! Apologies I meant probe impedance is 900MΩ (scope impedance is 1MΩ).
What further context would you need?
From the posts I believe I have found out the energy within the capacitor at a specific time during the pulse. Now what I would like to understand is...
OK the energy in the capacitor at any instant is ##CV^2(t)/2##.
How do I find the energy supplied to the capacitor at any time, and the total energy supplied to the capacitor, if I don't know the finite resistance you mention.
Yes your understanding is correct.
So how would I calculate the energy provided by the power source?
Would it be ##CV^2(t)##? Or would I need to find the sum of all ##CV^2(t)## over the whole pulse?
The pulse is repeating, with a set amount of time at zero voltage, so I took one wavelength. Yes the pulse is very similar to your image but not exact.
What would the scope image and schematic provide you? When you ask for frequency are you asking for pulse frequency or some other frequency...
OK. So leading on from this how would I calculate the energy required to charge that capacitor over that pulse?
If the energy within the electric field is at a specific point in time, the energy the source provides is CV^2, but do I have to add up all the specific point in times that the energy...
You are not saying that the width of the pulse has no effect? I'm confused even more now.
##π\frac{A}{B}## where A is the peak and B is the first zero point.