Q21.There are two orthogonal vectors A,B in R3, each of length 1 unit. Let P be a vector satisfying the equation P×B = A P − −, then-
Correct answer: P is orthogonal to B
Q22.The work done in a moving particle in the force field along the straight line from (0, 0, 0) to (2, 1, 3) is–
Correct answer: 16 units
Q23.The unit vector perpendicular to each of the vectors u = 2i 2j +k, v = i + j k − − − − is–
Correct answer: i + 3j + 4k/26
Q24.If the vectors i 3j 2k,2i j 4k and 3i 2j xk are coplanar, then the value of x is–
Correct answer: 2
Q25.Given that a and b are unit vectors. If the vectors p 3a 5b and q a b are mutually perpendicular then–
Correct answer: a, b have opposite directions
Q26.The projection of the vector i 2j k on the vector 4i 4j 7k is–
Correct answer: 19/9
Q27.Let a,b,c be there vectors such that a.(b c) b.(c a) c(a b) 0 and a 1, b 4 and c 8 then a b c equals–
Correct answer: 9
Q28.Let a ∧ and b ∧ be two unit vectors and θ be the angle between them. Which of the following will be value of cos 2 θ.
Correct answer: a b 2 ∧ ∧ +
Q29.If the vectors i– 3 j 7 k ∧ ∧ ∧ + x and i– y j– z k ∧ ∧ ∧ are collinear then the value of 2 xy z is equal to –
Correct answer: none of the above
Q30.If A and B are vectors such that B 5 = A and B 4i– 3k ∧ ∧ × = A then A.B is equal to –
Correct answer: 10 6
Q31.If () () () = + + θ ˆ ˆ ˆ r asint i acost j at tan k then the value of 2 × dr d r dt dt is-
Correct answer: a2/sec θ
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Q32.The value of () () () ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ i. j k j. k i k. i j × + × + × is-
Correct answer: 3
Q33.If a,b and c are three vectors in such a way that a + b + c = 0 and a = 1, b = 4, c = 2, then the value of () 2 a.b +b.c + c.a is equal to
Correct answer: –21
Q34.If A and B are two vectors, then angle between vectors A + B and A×B is
Correct answer: 90º
Q35.If â and b̂ are unit vectors such that ˆ â + 2b and ˆ ˆ 5a – 4b are perpendicular to each other, then the angle between â and b̂ is
Correct answer: 3/π
Q36.Find the value of 'a' such that the vectors ˆ ˆ ˆ ˆ ˆ ˆ 2i – j+ k,i + 2j – 3k and ˆ ˆ ˆ 3i + aj+ 5k are coplanar.
Correct answer: –4
Q37.The points with position vectors ˆ ˆ ˆ ˆ ˆ ˆ 60i + 3j,40i – 8j,ai – 52j are collinear if a is equal to
Correct answer: –40
Q38.The position vectors of the points A, B, C and D are ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ 3i – 2j – k,2i + 3j – 4k,–i + j+ 2k and ˆ ˆ ˆ 4i + 5j+ λk respectively. If the points A, B, C and D lie on a plane, the value of λ is
Correct answer: –146/17
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Q39.If () () () ˆ ˆ ˆ ˆ ˆ ˆ u = i × a×i + j× a× j +k × a×k then u is equal to
Correct answer: 2a
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Q40.If a, b, c are three unit vectors such that 1 a×(b× c) = b 2, then the angle which a makes with c is
Correct answer: 60°