Thermo quiz.

• Thermal expansion- This gap is called an "expression joint"and it allows the bridge to expand and contract.
• Bimetallic strips- two strips of different metals are riveted together.
• In a bimetallic, strip brass for contract, more about heated, then does so the strip bends as shown.
• Thermostats- used to control temperature.
• When the bimetallic coil expands the mercury rolls away from the electrical contacts, breaking the circuit.
• Glass- if one part of a piece of glass is heated or cooled more rapidly than adjacent parts the expansion or contraction may be break the glass.
• Borosilicate glass expands very little with increasing temperature.
• Telephone lines are longer in summer, when they are warmer and shorter in winter when they are cooler, they therefore sag more on how summer days than in water. If the telephone lines are not with enough in summer they might contract too much and snap during the winter.
• 100 degrees Celsius - boiling point.
• At 0⁰C Ice is less dense than water and so ice floats on water.
• Almost all liquids will expands when they are heated Ice- cold water, however, does just the opposite.
• Left- the collapsing crystals plus increased molecular motion with increasing temperature (center) combine to make water most dense at 4⁰C (right)
• The densest water- which settles at the bottom of a pond is 4⁰ C above the freezing temperature.
• Water at the freezing point 0⁰C is less dense and floats.
• Freezing water- Most of the cooling in a pond takes place at its surface then the surface water is cooled than the water.
• Consider a pond that is initially at say 10⁰C
• It cannot be cooled at 0⁰C without first being cooled at 4⁰C
• In a cold winter, the ice will be thinker than in a milder winter.