Engineering Applications and Consequences of Solid Expansion

Try these questions

5 questions from this lesson’s quiz. Start the lesson to answer them and see the right answers.

1. 1. Railway rails are joined by fishplates with oval (slotted) bolt holes instead of circular ones. Why?

   • A. So the bolts can slide as the rails expand and contract, avoiding stress
   • B. So the rails are held rigidly and cannot move at all
   • C. So the rails conduct electricity better along the track
   • D. So the rails become lighter and cheaper to transport

2. 2. A steel rail 50 m long has linear expansivity 1.2 \times 10^{-5} K^{-1}. By how many millimetres does it expand when its temperature rises by 30 K?

   Type your answer (in mm) in the lesson.

3. 3. Why should overhead telephone or power cables be installed slightly slack, not pulled taut, on a hot afternoon?

   • A. Taut cables would sag too much on hot days
   • B. Slack cables conduct electricity better
   • C. On cold nights the cables contract, and taut ones could snap or pull down poles
   • D. Metal cables only expand when they are pulled taut

4. 4. A bimetallic strip has brass (\alpha = 1.9 \times 10^{-5} K^{-1}) bonded on top of iron (\alpha = 1.2 \times 10^{-5} K^{-1}). What happens when it is heated?

   • A. It stays straight but becomes thicker
   • B. It curves upwards because iron expands more than brass
   • C. It curves downwards because iron expands more than brass
   • D. It curves downwards because brass expands more than iron

5. 5. What name is given to the severe bending or distortion of a steel rail when its thermal expansion is prevented and compressive stress builds up?

   Type your answer in the lesson.

More in Temperature and Thermal Expansion

• ▸Concept of Temperature and Temperature Scales
• ▸Liquid Expansion and Mechanical Thermometers
• ▸Electrical Temperature Sensing
• ▸Thermal Expansion in Solids
• ▸Thermal Expansion of Liquids
• ▸Anomalous Expansion of Water
• ▸Thermal Expansion of Gases
• ▸Thermal Expansion in Matter

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