Often items can be changed through variances in temperature

QUESTION

Often items can be changed through variances in temperature. There are a variety of methods using temperatures and friction reduction which can be quite useful in assembling or disassembling, especially with metal objects.a. You can remove a tight-fitting iron ring from around a copper cylinder by carefully heating only the iron ring. Why does this technique work?b. Even if you can’t heat the iron ring without heating the copper cylinder, you can free the ring from the cylinder by putting them both in liquid nitrogen, which has a temperature of –195° C. Why should this technique work?c. One scheme for making it impossible to remove an aluminum post from a hole in an aluminum plate involves temperature. If you start with a post that is slightly too wide to fit into the aluminum plate and then chill the post in liquid nitrogen, it will shrink enough to fit. When it warms up it will fit so tightly in the hole that nothing can remove it. Why won’t heating or cooling the post and plate make it possible to extract the post?d. If a nut has rusted shut, how could it be loosened to open?e. If a screw head is stripped, how could you remove the screw from wood? From metal?f. Why is a new jelly jar harder to open? An old Jelly Jar that has not been opened in a while can also be hard to open. Why are the new and the old jar different in why they are sealed and how could you aid opening the new and the old jar?

ANSWER:

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