An observer is on top of a lighthouse. How far from the foot of the lighthouse is the horizon that the observer can see?
Use the computer to model an epidemic. Try out public health policies to control the spread of the epidemic, to minimise the number of sick days and deaths.
Are these estimates of physical quantities accurate?
The bacteria divide twice an hour, so divide 48 times in 24 hours. Thus $2^{48}$ bacteria cells after 24 hours, assuming the bacteria split in two when they divide. X has half life of 10 mins, so there are $6\times 24$ half lives in 24 hours. We only consider the bacteria released near the end then, as very little from the beginning will be left after 24 hours. Now $10^{11}< 2^{48}$ so if Rudolph's nose was 4mL, his nose will certainly be glowing. Assuming instead that Rudolph's nose was 4mL, we need the concentration of bacteria to be $4\times 10^{11}$. After 23.5 hours there were $2^{47}$ cells and $2^{47}$ have just been released. Right at 24 hours, there will be $\frac {2^{47}}{2}+2^{48}$ cells, which is greater than $4\times 10^{11}$. So Rudolph will have a glowing nose.