Understanding Friction Between Surfaces
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Questions and Answers

What is friction?

  • Easy relative movement of surfaces
  • Resistance to motion (correct)
  • Presence of smooth surfaces
  • The absence of hills and valleys on surfaces

    • Why do lubricants reduce friction?

  • By creating more hills and valleys on surfaces
  • By separating surfaces with irregularities (correct)
  • By increasing interlocking surface irregularities
  • By increasing the weight of the surfaces

    • What purpose do lubricants serve, according to the text?

  • Increasing strength of materials
  • Promoting surface irregularities
  • Temperature control (correct)
  • Increasing corrosion

    • Why are friction reduction and wear reduction considered the most important lubricant purposes?

    <p>To prolong the life of interacting surfaces</p> Signup and view all the answers

    What causes surfaces to cling or weld together when they rub together?

    <p>The presence of hills and valleys on surfaces</p> Signup and view all the answers

    How do lubricants help with shock absorption?

    <p>By separating and cushioning surfaces</p> Signup and view all the answers

    What happens to the resistance to relative motion when lubricants are added between surfaces?

    <p>It decreases</p> Signup and view all the answers

    What is the term used to describe the extra force required when two surfaces rub against each other?

    <p>Force of friction</p> Signup and view all the answers

    How does the use of a lubricant affect the wear of surfaces?

    <p>Beneficially reduces wear</p> Signup and view all the answers

    What role do oils play in preventing corrosion of metal surfaces exposed to air?

    <p>Form a corrosion barrier film</p> Signup and view all the answers

    How do lubricants contribute to temperature control in bearings?

    <p>By reducing friction and heat</p> Signup and view all the answers

    Which function does a lubricant serve when gear teeth intermeshing experience impacts?

    <p>Absorb shock</p> Signup and view all the answers

    What is the purpose of using lubricants to provide sealing between pistons and cylinder walls?

    <p>Provide a seal</p> Signup and view all the answers

    Which factor can high temperatures in bearings lead to?

    <p>Loss of strength and hardness in bearing materials</p> Signup and view all the answers

    How does the presence of a lubricant affect the surfaces between which it is applied?

    <p>Forms a corrosion barrier film</p> Signup and view all the answers

    How do lubricants contribute to reducing wear between surfaces?

    <p>By separating the bearing surfaces to prevent contact</p> Signup and view all the answers

    What is the role of lubricants in corrosion reduction?

    <p>Forming a barrier film to prevent corrosion</p> Signup and view all the answers

    Why are lubricants essential for temperature control in bearings?

    <p>To reduce heat production by lowering friction</p> Signup and view all the answers

    How do lubricants help in shock absorption in cases like gear teeth intermeshing?

    <p>By acting as a cushion to absorb shock</p> Signup and view all the answers

    What happens to surface wear when lubricants are not used between the bearing surfaces?

    <p>Wear is increased due to large pieces being torn away</p> Signup and view all the answers

    What can happen to bearing materials under high temperatures?

    <p>Decrease in ability to support load</p> Signup and view all the answers

    What function do chemical compounds (additives) serve in lubricants?

    <p>To prevent the formation of acids due to oil oxidation</p> Signup and view all the answers

    How do lubricants help to prevent the wearing down of high spots on surfaces?

    <p>By separating the surfaces to avoid contact</p> Signup and view all the answers

    What is the primary reason for the resistance to relative motion between two surfaces?

    <p>The interlocking of surface irregularities</p> Signup and view all the answers

    What is the main result of the interlocking of surface irregularities?

    <p>Resistance to relative motion</p> Signup and view all the answers

    What is the primary function of lubrication in relation to friction?

    <p>To separate surfaces with interlocking irregularities</p> Signup and view all the answers

    What happens to the surfaces when lubricants are added between them?

    <p>The surfaces move freely in relation to each other</p> Signup and view all the answers

    What is the purpose of lubricants besides friction reduction and wear reduction?

    <p>Shock absorption and temperature control</p> Signup and view all the answers

    What is the result of the interlocking of surface irregularities on the force required to move the surfaces?

    <p>The force required is increased</p> Signup and view all the answers

    What is the term used to describe the phenomenon where surfaces cling or weld together?

    <p>Friction</p> Signup and view all the answers

    What is the origin of fixed oils?

    <p>Animal or vegetable origin</p> Signup and view all the answers

    What is a characteristic of synthetic oils?

    <p>Resistant to sludge formation and oxidation</p> Signup and view all the answers

    Where are the heavy oils drawn off in the fractionating tower?

    <p>Near the bottom of the tower</p> Signup and view all the answers

    What is a common use of fixed oils?

    <p>Incorporated into greases or mixed with mineral oils</p> Signup and view all the answers

    What is the most commonly used class of lubricants?

    <p>Mineral oils</p> Signup and view all the answers

    What is the purpose of using grease in lubrication?

    <p>To provide a permanent protective coating and seal out dirt and water</p> Signup and view all the answers

    What type of lubricant is suitable for high temperature service and is water resistant?

    <p>Barium &amp; Lithium Base Greases</p> Signup and view all the answers

    What is the primary characteristic of semi-solid lubricants or greases?

    <p>They have a thick, stiff consistency</p> Signup and view all the answers

    What type of lubricant is used for heavily loaded machinery that operate at slow speeds?

    <p>Specialty greases</p> Signup and view all the answers

    What is the primary advantage of using grease over liquid lubricants?

    <p>It is more convenient to handle and replenish</p> Signup and view all the answers

    Which property of lubricants is emphasized depending on the particular application?

    <p>Physical stability under variations of temperature and pressure</p> Signup and view all the answers

    Under what conditions are solid lubricants typically suitable for use?

    <p>Heavy loads and extreme temperatures</p> Signup and view all the answers

    Which of the following is a source of synthetic oils?

    <p>Chemical synthesis processes</p> Signup and view all the answers

    What is the primary reason for categorizing lubricants into different classes?

    <p>Service requirements</p> Signup and view all the answers

    For what purpose might solid lubricants be used in addition to their thermal properties?

    <p>Lubricating bearings in storage</p> Signup and view all the answers

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