Thank you for watching the video. Start Your Free Trial Learn more. Matt Jones M. Explanation Transcript Most matter expands when heated and contracts when cooled, a principle called thermal expansion.
Physics Heat and Thermodynamics. Science Biology Chemistry Physics. English Grammar Writing Literature. All Rights Reserved. First, in more than one textbook I have seen a false example of thermal expansion.
The picture shows some rail road tracks that are warped and bent out of shape. The caption says that they buckled due to thermal expansion. Actually, buckling of this severe nature is almost always due to an earthquake.
Just saying. In the picture at the top of this post, there is an old style thermostat. It's a pretty simple device. The metal coil expands as the temperature increases. This expansion in the coil means that the glass tube at the top will be tilted at a different angle.
Inside the tube are two wires one at each end and some mercury. When the tube is close to horizontal, the liquid mercury will come in contact with both wires and "turn on" your air conditioner. Pretty simple. Well, it's also pretty bad if you break it since there is mercury in there. New thermometers mostly use a simple computer and temperature sensor to make a non-mechanical and without mercury thermostat. I'm not so sure in this case, but some of these thermostats use a bimetallic strip.
This strip would have one type of metal on one side and another type on the other. As the temperature changes the two metals expand different amounts and cause the strip to bend. View Iframe URL. In this case, the road expanded in length as the temperature increased in the summer. If the road has no where to expand, it will eventually buckle as shown above.
Buckling is bad at highway speeds. There is one other example. This one is a popular demonstration. Here you take a brass ball and a brass ring. If you heat the ball, it won't fit through the ring. Check it out. And there you have it. Thermal expansion. A few final notes: First, I hate the words "heat" and "heated". They aren't really wrong, but they are used incorrectly in many cases. In the past, I called it a four letter word.
Next note - what about thermal expansion of liquids and gases? Some of the same ideas apply for liquids - but gases are a pretty different story. Still, they do expand with an increase in temperature usually. Finally, here is a homework assignment for you. Remember that I usually assign tasks that I want to do myself but I haven't done yet. See if you can make a model I would suggest in VPython of a one dimensional solid. The solid would consist of balls that are connected by springs.
However, in this case the springs would follow the Morse potential instead of the usual Hooke's Law. Then as you increase the average starting kinetic energy of the masses, the solid should get longer. With this ball and spring model, we can explain: The contact force with some solid isn't constant. The more something pushes against material, the greater this constant force becomes.
When you pull on a metal, it stretches. The speed of sound is different in different materials. This is why we use this model - because it's useful in some situations. Explanation: Heating is an increase in energy, An increase in energy may break bonds causing a chemical reaction or a change in state.
The more the kinetic energy the more motion that there is in the matter An increase in motion causes the molecules to move apart causing the matter to expand. Atika Khan. Apr 13, Explanation: matter expands when it is heated. Related questions Can matter be destroyed? What are the properties of matter? How does matter differ from weight? How does matter affect sound? How can I calculate the amount of matter in a given volume? How does matter change from one state to another?
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