Civil Services Prep

Prelims 2013 · Science and Technology · Question 38

Ball bearings are used in bicycles, cars, etc., because

  1. the actual area of contact between the wheel and axle is increased
  2. the effective area of contact between the wheel and axle is increased
  3. the effective area of contact between the wheel and axle is reduced
  4. None of the above statements is correct

Answer

the effective area of contact between the wheel and axle is reduced

  • (a) Ball bearings do not increase the actual contact area in a useful sense; they replace sliding contact with rolling contact. Verdict: Incorrect.
  • (b) They do not increase the effective area of contact; the purpose is to reduce friction. Verdict: Incorrect.
  • (c) Ball bearings reduce the effective area of contact and convert sliding friction into much smaller rolling friction. Verdict: Correct.
  • (d) Since option (c) is correct, this is false. Verdict: Incorrect.
  1. Which of the following statements with regard to genetic medicine is/are correct ? 1. Genetic medicines…
  2. Which of the following statements with regard to Large Language Models (LLMs) used in machine learning is/are…
  3. Which of the following statements with regard to stealth technology is/are correct ? 1. Stealth objects have a…
  4. Which of the following statements with regard to Black Boxes used in modern aircrafts is/are correct ? 1. They…
  5. Consider the following statements with regard to involvement of private entities in India's space programme :…
  6. Which of the following statements with regard to drone swarms is/are correct ? 1. They use Terahertz band of…