By signing in you confirm you are 18 or older, or have your parent’s or guardian’s consent.

NDA 1 2024 Maths, question 68

Topic: Vectors

Q68

Consider the following in respect of moment of a force :

  1. The moment of force about a point is independent of point of application of force.

  2. The moment of a force about a line is a vector quantity.

Which of the statements given above is/are correct ?

  1. (a) 1 only
  2. (b) 2 only
  3. (c) Both 1 and 2
  4. (d) Neither 1 nor 2Correct answer

Solution.

Answer: (d) Neither 1 nor 2

  1. For a fixed reference point O, the moment is r × F, where r runs from O to the force’s point of application.
  2. Moving the application point arbitrarily can change this moment; only movement along the same line of action leaves it unchanged.
  3. Moment about a line is the scalar projection of r × F along that line.
  4. Thus both unrestricted statements are false.