Temperature and Thermal Expansion

The liquid in a thermometer ______________ as the temperature increases.

• expands
• disappears
• freezes
• explodes

What is Thermal Contraction

• The movement of particles.

• A decrease in a materials volume when its temperature decreases

• The movement of fluids in a cycle because of convection

• A material through which thermal energy does not flow easily.

When objects contract upon cooling...

• volume increases and density increases.
• volume increases and density decreases.
• volume decreases and density decreases.
• volume decreases and density increases.

Convert: 25.0 ^oC to ^oF:

• 77 F
• 77 C
• 100 F
• 100 C

Calculate the change in length of a 100mm aluminium bar that has increased in temperature by 55⁰C.  
Take the coefficient of expansion to be 25 x 10^-6

• 0.258mm
• 0.1375mm
• 1.23mm
• 1.37mm

Calculate the change in temperature of an 900mm aluminium bar, that has increased in length to 901.035mm.
 α = 25 x 10^-6

• 12^oC
• 34.5^oC
• 57^oC
• 46^oC

The length of copper wire at 20^oC is 4.5m. Calculate its new length when the temperature is 95^oC. Given α = 1.7×10^{-5 o}C^-1

• 4.55m

• 5.41m

• 5.11m

• 4.505m

A silver plate of 16cm2 is heated from 20 degrees to 100 degrees. What is the increase of area?
assume  $\alpha=2\times10^{-5}$  

• 0.051

• 16.051

• 0.0256

• 16.0256

Alex noticed that a metal door that sticks on hot days does not stick when it cools off at night. This is because the metal contracts as it cools. The reason for this is that, as the metal cools, the atoms:

• become smaller and take up less space
•  slow down and move closer together
• merge together to form fewer atoms
• speed up and move farther apart