Give two applications of expansion and contraction of materials.
Answers
Answer:
Applications of Expansion and Contraction
Expansion by heating can be used in several everyday activities. The jammed metal lid of a jam jar can be opened by heating. ... The fact that materials expand on heating is used in thermometers. In many thermometers, mercury is used.
Answer:
Applications of expansion and contraction in solids
1: Railway lines
Railway lines are fixed with gaps to allow for expansion when temperature rises. The bolt holes are also oval in shape for the same reason. Another way of creating room for expansion in railway lines is by planing the ends of the rails so that they are able to overlap during expansion.
2: Telephone/electricity wires
Telephone and electricity wires are loosely fixed during installation to allow for contraction during cold weather.
3: Steam pipes
Pipes carrying steam from boilers are fitted with expansion loops to allow for expansion and contraction.
Without the loop the pipe is likely to break due to the resultant force as a result of expansion and contraction. It is necessary that oil companies make this allowance when constructing fuel pipelines.
4: Steel bridges
In the construction of steel bridges, one end is fixed while the other end is placed on rollers. This is to allow for expansion and contraction.
5: Rivets
Rivets are fitted when hot and then hammered flat. On cooling, the rivet contract, pulling the two plates firmly together.
6: Thermostat
It is a device that can be used to control the temperature of a room. It uses a bimetallic strip. It is connected to a heater circuit. When the temperature of the room rises beyond the set value, the bimetallic strip expands and bends away breaking the contact. Hence the heater circuit is switched off.
The strip cools and contracts and the contact is remade switching on the heater circuit. The setting knob is used to adjust the temperature at which the thermostat is switched on and off