Question 110Asked in BPSC TRE 1.0 (2023) Mathematics Class 11-12

The moment of the force 3î + k̂, whose line of action passes through the point 2î − ĵ + 3k̂, about the point î + 2ĵ − k̂, isबल 3î + k̂, जिसकी क्रिया-रेखा बिन्दु 2î − ĵ + 3k̂ से होकर जाती है, का बिन्दु î + 2ĵ − k̂ के परितः आघूर्ण है

बल 3î + k̂, जिसकी क्रिया-रेखा बिन्दु 2î − ĵ + 3k̂ से होकर जाती है, का बिन्दु î + 2ĵ − k̂ के परितः आघूर्ण है
  1. A3î − 11ĵ − 9k̂3î − 11ĵ − 9k̂
  2. B−3î + 11ĵ + 9k̂−3î + 11ĵ + 9k̂
  3. C−3î + 11ĵ − 9k̂−3î + 11ĵ − 9k̂
  4. DMore than one of the aboveउपर्युक्त में से एक से अधिक
  5. ENone of the aboveउपर्युक्त में से कोई नहीं
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Correct answer: (B) −3î + 11ĵ + 9k̂−3î + 11ĵ + 9k̂

Explanation

r⃗ = (2î − ĵ + 3k̂) − (î + 2ĵ − k̂) = (1, −3, 4). Moment = r⃗ × F⃗ = (1, −3, 4) × (3, 0, 1) = (−3 − 0, 12 − 1, 0 + 9) = −3î + 11ĵ + 9k̂.r⃗ = (2î − ĵ + 3k̂) − (î + 2ĵ − k̂) = (1, −3, 4)। आघूर्ण = r⃗ × F⃗ = (1, −3, 4) × (3, 0, 1) = (−3 − 0, 12 − 1, 0 + 9) = −3î + 11ĵ + 9k̂।

From BPSC TRE 1.0 (2023) Mathematics Class 11-12 — Previous Year Paper

This is question 110 of BPSC TRE 1.0 (2023) Mathematics Class 11-12 — Previous Year Paper. See all questions of this paper with answers, or attempt the paper as a timed online test to get your score and all-India rank.