NATS 1945 Lecture Notes - Lecture 2: Thermal Expansion, Pyrex, Boron

• School: York University
• Department: Natural Science
• Course: NATS 1945
• Professor: Robin Metcalfe

Document Summary

Substance expand when heated and contract when cooled (increased vibrations push molecules apart, and vice versa) Conversely, when heat is removed from the objects, the molecules slow down allowing their bonds to strengthen so the molecules get tighter together, and the object, as a whole, contracts. In the same way some substance conduct heat better than others, some substances expand or contract more easily than others. We can assign a value to a substances ability to expand or contract, and that value is called the coefficient of thermal expansion. That number is a measure of the amount that a particular substance will expand or contract due to, a 1o degree change in t. A substances ability to expand or contract has to do with its molecular composition, so(cid:373)e (cid:373)ole(cid:272)ules are glued together (cid:373)ore tightl(cid:455) tha(cid:374) other a(cid:374)d so the(cid:455) just do(cid:374)"t (cid:373)o(cid:448)e apart as easily. Amount of expansion depends on type of substance.