One way of shortening the time to bake a potato is to put a

One way of shortening the time to bake a potato is to put a stainless steel nail through the potato and put it in the oven. Determine how much faster this will cook the potato. State your assumptions. Would other metal nails work better?

Solution

The type of nails we are talking about here is Potato nails. They are meant for use in baking potatoes. First of all, let me clear one thing that these potato nails are made of food-grade metals.

Now as sccording to the question, potato is being baked in oven with stainless steel nail peirced through it. Lets compare two scenarios - potato with and without nail.

Potato without nail gets heat on the outer surface first. As the outer part softens, heat moves to the inner part. Lets assume it takes 20 mins to bake one potato without nail.

Now lets take potato with nail, Here assume that nail is long enough that some part of it is extended at the both ends of potatoes. This exposed part of nail will take all the heat of oven. Now due to conduction the heat will move through the metal heating the entire nail and core of potato. Here two things are happening simultaneously,

1. Outer surface is getting heat directly from the oven.

2. inner surface is getting heat from the pierced nail.

Clearly potato has less thermal conductivity than steel, so the time would greatly reduce in second case ( with nail). It will take around 12-14 mins at same temperature.

We can use aluminum grade nails also. The aluminium nail will take less time then steel nail Because aluminium has high thermal conductivity. At temperature of 20 degree celcius, it has around 203.5 W/mK whereas stainless steel has only around 40 W.mK. Try with aluminium also. however, all the metals have their own drawbacks like inside color may change with aluminium nail but it doesn\'t matter. :-)