Question 3 This snow storage is a real thing] A Swiss company are contracted by most winter Olympic games and other major ski competitions to store snow from the previous winter in case of emergency. When I first read this. I thought it was totally ridiculous. so naturally I had to do the calculations to see if it was at all feasible... How much snow would we need? I'm guessing a minimum would be ten ski runs, each roughly 10m wide 1km longII and with the snow around 10cm deep. Clearly you'd like moreII but that should be enough for competitions to happen. Snow is much less dense than water. The actual density varies enormously: from light and uffy new-fallen snow to dense snowballs. But a quick web search indicates d1ata density of around 50 kg per cubic metre is probably reasona ble. So how many cubic metres of snow do you need to store? Answer: How could we store it?I Refrigerated warehouses would be one way-but would be extremely expensive-and you could just cool down some water and spray it out without bothering with storage. So is there a cheaper approach that would make storage feasible? How about we nd a shady gully somewhere on the mountain and bulldoze the snow into it. Then cover it with a layer of straw as insulation-would it last through the summer? This would certain ly be cheap. but would snow really survive that long? I know that on Mt Kosciuszko. deeper snowdrifts ca l'l last all summer, and that's a relatiuerwarm location and with no insulation - so this is feasible. Imagine the gully is 10m deep.10m wide. and will fill a 100m length of it with snow {to give our 104 cubic metres}. And we'll cover it with a layer of straw 10cm deep. I'll assume that the ground below the snow remains at a temperature below zero all summer, so the only heel Ioes will be through the top. I'll also assume an average sumr'ner temperature of 100 {it is high on a mountain and this will be an average of day and night]. The conductivity of the straw will be about the same as that of air, {as it's mostly the air gaps doing the insulation}I i.e. k~0.025 mefK. How much power is conducted through the straw. when the temperature is 0 C inside and 10!: outside? Enter your answer in Watts. Answer: So what is the total heat that gets through the straw all summer? Assume that summer is 3 months long. Type scientific notation using the "e" format, i.e. 3.4 x 107 would be written 3.4e7. Answer: Check That sounds like a lot. But is it? To melt snow, we'll need to raise it to OC from whatever sub-zero temperature it started at, and then supply the latent heat (-3x105 J/kg). The heat capacity is relatively small, so let's ignore it. What mass of snow will melt? Enter your answer in tonnes (a tonne is 1000 kg). Answer: Check That sounds like a lot, but if you compare with the total mass, it's only around 10%. So you could just pile up 10% more at the start and you'll be fine! You would need to make sure the melting snow can drain away (easy if you are in a gully), and perhaps put a plastic sheet over the straw to make sure it doesn't blow or wash away, and to stop any rain from melting the snow. And that is actually how they do this