Q221.What is the value of the cosine of the angle between the vector ˆ ˆ ˆ 2i 2j k + + and the X-axis?
Correct answer: 2/3
Q222.If ˆ ˆ ˆ â 2i j 3k = + + and ˆ ˆ ˆ ˆ b 3i 2j k = − + are two vectors. Then teh angle between them –
Correct answer: 600
Q223.If ˆ ˆ ˆ a 6i 4j 4k = + + and ˆ ˆ ˆ b 2i 4j 3k = + + then, what will be the value of b a ×?
Correct answer: ˆ ˆ ˆ 4i 10j 16k + −
Q224.If two forces ˆ ˆ ˆ 4i j 3k + − + − and ˆ ˆ ˆ 3i j k + − + − are acting ona particle due to which the particle is displaced from the point ˆ ˆ ˆ i 2j 3k + + + + to ˆ ˆ ˆ 5i 4j k + + + + then the total work done by the force is:
Correct answer: 40 units
Q225.If a 5, a b 8 = − = and a b 10 + = then what will be the value of b?
Correct answer: 57
Q226.If a b c 1 = then the value of a.b c b.c a c.a b c a.b a b.c b c.a × × × × × × × × × × × × + + × × × × × × × × × × × × is:
Correct answer: 3
Q227.If the position vectors of vectors A and B are a and b respectively, then what will be the position vector of the mid-point of AB?
Correct answer: () 1 a b 2 +
Q228.If the vectors ˆ ˆ ˆ 2i j k + + + + and ˆ ˆ ˆ i 4j k − + λ − + λ − + λ − + λ are perpendicular to each other, then what will be the value of --?
Correct answer: 2
Q229.Nodulus of the vector ˆ ˆ ˆ ĉ 4i 5j 11k = − + is:
Correct answer: 9 2
Q230.If two vectors are a b − and a b + then heir cross product () () a b a b − × + will be:
Correct answer: () 2 a b ×
Q231.The vectors p,q,r are coplanar, if and only if:
Correct answer: () p q.r 0 × =
Q232.The vectors: <1, –2, 1>, <2, 1, –1> and <7, –4, 1> of R3 are:
Correct answer: linearly dependent
Q233.a b × × is:
Correct answer: a vector quantity perpendicular to the plane containing a and b
Q234.The value of ((())) ((()) 2 2 a b a.b × + × + is:
Correct answer: a2/b2
Q235.If the vector ˆ ˆ ˆ ˆ ˆ ˆ ai j k,i bj k + + + + + + + + + + + + + + + + and ˆ ˆ ˆ i j ck + + (where a≠b≠c≠1) are coplanar, then the value of 1 1 1 1 a 1 b 1 c + + − − − − − − − − − − − − is;
Correct answer: 1
Q236.If u and v are unit vectors and θ is acute angle between them, 2u 3v × × is a unit vector for
Correct answer: exactly one value of θ
Q237.Vectors ˆ ˆ ˆ ˆ ˆ ˆ 2i j k,i 2j 3k − + + − − + + − − + + − − + + − and ˆ ˆ ˆ 3i pj 5k + + are coplaner. Then p is
Correct answer: –4
Q238.If a and b are two unit vectors inclined at an angle θ, then sin 2 θ =
Correct answer: None of the these
Q239.The direction cosines of the vector ˆ ˆ ˆ 3i 4j 5k − + − + are
Correct answer: 3 4 1,, 5 2 5 2 2 −
Q240.Let ˆ ˆ ˆ a i j k = + + λ = + + λ = + + λ = + + λ and ˆ ˆ ˆ b i j k = + + = + + = + + = + + then a b a b + = + + = + + = + + = + holds for λ
Correct answer: λ = 1