Hot Matter

Question 1

Lurking below the surface of our seemingly solid existence is …

Answer 1

… an atomic world in constant motion

Question 2

Heat

Answer 2

is the flow of this energy from the atoms of one object to the atoms of another

Question 3

Why thermometer

Answer 3

fluid in a thermometer — usually mercury or alcohol — transfers heat easily so it quickly matches the temperature of its surroundings

Question 4

Consider a row of rods lined up end to end:

As the temperature drops, what will happen to the gap between the rods?

Answer 4

It increases

Question 5

When an object is heated, it expands …

Answer 5

… along every dimension

Question 6

There are two dots on this sheet of metal. How will the distance between them change as the sheet is heated?

Answer 6

It increases

Question 7

Consider a metal plate with a hole in it. As it’s heated, the length and width of the plate increase as it expands.

How does the diameter of the hole change as the plate is heated?

Answer 7

It increases

Question 8

Now consider this metal plate with two large holes next to each other:

As the plate is cooled, how will the distance between the dots change?

Answer 8

It decreases

Question 9

You have two rings made up of the same metal, which you’d like to interlock with each other.

Unfortunately, the gap in one ring is slightly too small to fit the other ring through.

If you want to slip the solid ring through the opening in the other, should you heat or cool the ring that has the opening?

Answer 9

Heat

Thermal expansion occurs equally in all dimensions meaning that the shape of an object will not change and any gaps or holes will increase in size.
So to increase the size of the gap in the ring, the ring must be heated.

Question 10

coefficient of thermal expansion

Answer 10

how much a substance expands per degree of temperature increase.

Question 11

The coefficient of thermal expansion of the glass jar is higher than that of the wooden lid.

How can you make the lid easier to remove?

Answer 11

By cooling the lid and the jar

If you heat the lid and the jar, then the jar will expand more than the lid does — which would make the lid of the jar even tighter and more difficult to open.

If you cool the lid and the jar, then the jar will contract more than the lid does, leaving the lid relatively large compared to the jar and easier to remove

Question 12

How does the bimetallic strip change as it’s heated?

The thermal expansion coefficient of copper is greater than that of iron.

Answer 12

The strip bends on the side of the iron

Bc the copper strip increases faster than the iron strip

Question 13

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