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Vector Practice Test 1 ( Addition of Vector )
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1 / 74
Which statement about vector addition is correct?
Explanation:A vector is defined by its magnitude and direction together. When vectors are added, both their sizes and directions are combined. So vector addition always takes magnitude and direction into account.
2 / 74
A vector of magnitude 13 units has components 5 units and 12 units along two perpendicular axes. These two components are
Explanation:The components are mutually perpendicular. Magnitude of the original vector is found by R = √(5² + 12²). R = √(25 + 144) = √169 = 13 units. So the components combine by the Pythagorean relation to give the original vector.
3 / 74
A force of 10 N is resolved into two perpendicular components 6 N and 8 N. When these two components are added back vectorially, the resultant is
Explanation:The components are at right angles, so R = √(6² + 8²). R = √(36 + 64). R = √100 = 10 N. So the components recombine to give the original 10 N.
4 / 74
If three vectors acting on a particle add to give zero resultant, the vectors can be represented graphically as
Explanation:Zero resultant requires that the final head comes back to the initial tail. When three vectors are arranged head-to-tail and close to form a triangle, this condition is met. Thus three vectors giving zero sum are represented as a closed triangle.
5 / 74
When resolving a vector into components and adding vectors by components, the resultant vector’s components along x- and y-axes are obtained by
Explanation:Each vector is first split into its x- and y-components. All x-components are combined algebraically to get the resultant x-component. Similarly all y-components are combined to get the resultant y-component. These two components together define the resultant vector.
6 / 74
Two vectors A and B are represented by two adjacent sides of a parallelogram. The diagonal passing through their common point represents
Explanation:In the parallelogram law, A and B are drawn from the same point as adjacent sides. A parallelogram is completed on these two vectors. The diagonal from the common tail gives the vector sum A + B.
7 / 74
A particle is acted upon by three displacement vectors that form three sides of a triangle taken in order. The net displacement of the particle is
Explanation:When vectors are arranged head-to-tail and form a closed triangle, start and end points coincide. This means there is no overall change in position. So the resultant or net displacement is zero.
8 / 74
The polygon law of vector addition is useful for
Explanation:Polygon law is an extension of the triangle law. Vectors are placed head-to-tail in sequence to form a polygon. The side joining the first tail and the last head gives the resultant. This law allows addition of any number of vectors together.
9 / 74
Which of the following cannot be a possible resultant when two vectors of magnitudes 6 units and 10 units are added?
Explanation:Resultant magnitude must lie between |10 – 6| and 10 + 6. So it must be between 4 and 16 inclusive. Values 4, 10 and 16 fall in this range and are possible. A magnitude of 2 units is less than 4, so it is not possible.
10 / 74
Vector addition is
Explanation:Commutative property means A + B = B + A, which holds for vectors. Associative property means (A + B) + C = A + (B + C), which also holds. Therefore vector addition is both commutative and associative.
11 / 74
A displacement of 3 km north and 4 km east gives a resultant direction
Explanation:The components are 4 km east and 3 km north. Resultant lies between north and east. Larger component is along east, so direction is closer to east. This is described as a direction east of north.
12 / 74
For two vectors A and B, if |A + B| = |A – B|, then the angle between A and B is
Explanation:Use the identities |A ± B|² = A² + B² ± 2AB cosθ. Given |A + B|² = |A – B|², the 2AB cosθ terms must cancel. That is possible only if cosθ = 0. So the angle between A and B is 90°.
13 / 74
Two vectors of magnitudes 5 and 5 act at a right angle. The magnitude of their resultant is
Explanation:The two vectors are equal and perpendicular. For perpendicular vectors, R = √(A² + B²). Here R = √(5² + 5²). R = √(25 + 25) = √50. So the magnitude of the resultant is 5√2.
14 / 74
A person walks 6 km east and then 8 km west. The magnitude of his resultant displacement is
Explanation:Take east as positive direction and west as negative. Net displacement = 6 – 8 = –2 km. Negative sign shows direction is towards west. Magnitude of displacement is 2 km.
15 / 74
When two vectors are added and the resultant has magnitude zero, the polygon representing these two vectors must be
Explanation:Zero resultant means net effect of the two vectors is nothing. Graphically, one vector must exactly cancel the other. This appears as two equal arrows on the same line pointing in opposite directions. So they overlap on a straight line segment with opposite arrows.
16 / 74
For two vectors of magnitudes 7 and 24, the resultant has minimum possible magnitude when the angle between them is
Explanation:Minimum resultant occurs when vectors act in opposite directions. Opposite directions correspond to an angle of 180° between them. So for magnitudes 7 and 24, the least resultant is obtained at 180°.
17 / 74
The minimum possible magnitude of the resultant of two vectors A and B is
Explanation:Resultant is smallest when the vectors point in opposite directions. Then the effective magnitude is the difference of their magnitudes. Thus the minimum possible resultant is ||A| – |B||, written as |A – B|.
18 / 74
If R is the resultant of two vectors A and B, then the maximum possible value of R is
Explanation:Resultant is largest when the vectors point in the same direction. In that case their magnitudes simply add. So maximum R is |A| + |B|, which we write as |A + B|.
19 / 74
In the triangle law of vector addition, the two vectors are represented by two sides of a triangle taken in order. The third side taken in the opposite order represents
Explanation:First vector is drawn from a point, and the second is drawn from the head of the first. These two sides in order represent the two vectors being added. The side joining the tail of the first to the head of the second gives the sum. Thus the third side of the triangle taken in opposite order represents the resultant.
20 / 74
The graphical method that uses a parallelogram to find the sum of two vectors is called
Explanation:Two vectors are drawn from a common point as adjacent sides of a parallelogram. A parallelogram is then completed on these two sides. The diagonal passing through the common tail gives the sum of the vectors. This construction is known as the parallelogram law of vector addition.
21 / 74
A body is acted upon by two forces 5 N north and 12 N east. The magnitude of the resultant force is
Explanation:Forces towards north and east are at right angles. So we use the Pythagorean relation for perpendicular vectors. R = √(5² + 12²). R = √(25 + 144) = √169. Thus the resultant force has magnitude 13 N.
22 / 74
The condition for two non-zero vectors A and B to give a zero resultant (A + B = 0) is
Explanation:A + B = 0 means that the two vectors cancel each other exactly. For this to happen, one must be equal in length but opposite in direction to the other. Geometrically they are collinear but point in opposite directions. So they are antiparallel with equal magnitudes.
23 / 74
Two vectors 10 N and 6 N act in opposite directions along the same line. The magnitude of their resultant is
Explanation:Opposite collinear vectors subtract in magnitude. Take the larger force direction as positive. Net magnitude is |10 – 6|. So the resultant force has magnitude 4 N.
24 / 74
Two vectors A and B are collinear and in the same direction. Their resultant has magnitude
Explanation:Collinear vectors in the same direction simply add in magnitude. The total effect is obtained by adding their lengths. So the magnitude of the resultant is |A| + |B|. This is written as A + B when we talk about magnitudes only.
25 / 74
When two vectors A and B are added head-to-tail, the resultant vector
Explanation:In the head-to-tail method, the tail of B is placed at the head of A. The free tail is at the start of A and the free head is at the end of B. The resultant vector is drawn from the free tail to the free head. So it starts from tail of A and ends at head of B.
26 / 74
The angle between two equal vectors whose resultant has the same magnitude as any one of them is
Explanation:Let each vector have magnitude A and angle between them be θ. Resultant magnitude is R = √(A² + A² + 2A² cosθ). Condition is R = A, so A² = 2A²(1 + cosθ). Dividing by A² gives 1 = 2(1 + cosθ), so 1/2 = 1 + cosθ. Thus cosθ = –1/2 and θ = 120°.
27 / 74
Two equal vectors of magnitude 5 units act at 60° to each other. The magnitude of their resultant is
Explanation:For any two vectors A and B with angle θ, resultant is R = √(A² + B² + 2AB cosθ). Here A = B = 5 units and θ = 60°. So R² = 25 + 25 + 2(5)(5) cos60°. cos60° = 1/2, so R² = 50 + 50/2 = 50 + 25 = 75. Therefore R = √75 = 5√3 units.
28 / 74
Two vectors 6 N and 8 N act at right angles. The magnitude of their resultant is
Explanation:The two forces are mutually perpendicular. For such vectors, resultant R = √(A² + B²). Here R = √(6² + 8²). R = √(36 + 64) = √100. So the magnitude of the resultant is 10 N.
29 / 74
Two displacement vectors 4 m east and 3 m north act on a body. The magnitude of the resultant displacement is
Explanation:The two displacements are at right angles to each other. For perpendicular vectors we use Pythagoras to find the resultant. R = √(4² + 3²). R = √(16 + 9) = √25. So the magnitude of the resultant displacement is 5 m.
30 / 74
For any nonzero scalar k, the vector kA is ______ to A.
Explanation:
Scalar multiples of A always lie along the same line as A, so kA is parallel to A.
31 / 74
The magnitude of the vector 3A is
|3A| = |3|·|A| = 3·|A|
32 / 74
If a vector is multiplied by a scalar k then the resultant may be
• If k=0, kA = 0 (the zero vector).• If k>0, kA points in the same direction as A.• If k<0, kA points opposite to A (–kA).
33 / 74
Two vectors are said to be collinear if the angle between them is
Collinear vectors lie along the same line, so they point in exactly the same (0°) or exactly opposite (180°) direction
34 / 74
The magnitude of the cross product A × B is given by
|A × B| = A B sin θ, with θ the angle between A and B.
35 / 74
The vector having zero magnitude and arbitrary direction is called
A “zero vector” has zero length and its direction is undefined; it is also called the “null vector.”
36 / 74
The cross product A × B of two parallel vectors is:
|A × B| = AB sin θ, and sin 0° = 0, so the result is the zero vector.
37 / 74
The dot product A · B of two perpendicular vectors is:
A · B = AB cos θ, and cos 90° = 0, so the result is 0.
38 / 74
A unit vector is defined as a vector whose magnitude is:
A unit vector has been scaled so its length is exactly 1.
39 / 74
Adding any vector A to the zero vector 0 gives:
A + 0 = A by definition of the zero vector.
40 / 74
If two perpendicular vectors of magnitudes A and B are added, the magnitude of the resultant R is:
By Pythagoras’ theorem (since the angle is 90°), |R| = √(A² + B²).
41 / 74
Vector addition is commutative. That means:
“Commutative” means you can swap the order of the vectors without changing the resultant: A + B = B + A.
42 / 74
Addition of vectors obey the law of _____
Graphical vector addition is done by placing the tail of one vector at the head of the other (head-to-tail). This is neither a scalar “simple addition” nor a product operation.
43 / 74
Two forces each of 10 N act at angles of 0° and 90° to the x-axis. What is the magnitude of their resultant?
F₁ at 0° has components (10, 0), F₂ at 90° has (0, 10).Resultant R = (10 + 0, 0 + 10) = (10, 10),|R| = √(10² + 10²) = √200 ≈ 14.14 N
44 / 74
Unit vector along the vector 4î + 3ĵ is _____
Unit vector along 4î + 3ĵ , is obtained by dividing the present vector by its magnitude.
The magnitude of the given vector is 5. Hence, the required unit vector is (4î + 3ĵ)/5.
45 / 74
When two vectors in the same direction are added, the magnitude of resulting vector is equal to _______
Consider the graphical representation of these two vectors. When one vector is added to the other in the same direction, the lengths will be added.
The resultant vector will bear the resultant length. Length is the magnitude of the vector. Hence the magnitudes add to give the magnitude of the resultant vector.
46 / 74
Following sets of three forces act on a body. Whose resultant cannot be zero
For three forces to have zero resultant, their magnitudes must satisfy the triangle inequality.
(each pair’s sum ≥ the third).
Here 10 + 20 = 30 < 40, so they can’t form a closed triangle and cannot balance to zero.
47 / 74
When subtracting B = 4î + 2ĵ from A = î – 6ĵ, the resultant A – B is:
A – B = (î – 6ĵ) – (4î + 2ĵ)= î – 6ĵ – 4î – 2ĵ= (1 – 4)î + (–6 – 2)ĵ= –3î – 8ĵ
48 / 74
If u and v are perpendicular unit vectors, then |u – v| equals:
|u| = |v| = 1 (unit vectors)Angle between u and v = 90° (perpendicular)
Use the formula:|u − v|² = |u|² + |v|² − 2|u||v|cosθ
= 1² + 1² − 2(1)(1)cos(90°)= 1 + 1 − 0= 2
Therefore,|u − v| = √2
49 / 74
A plane flies 300 km due north and then 400 km due west. Its resultant displacement is:
R = √(300² + 400²) = 500 km.
50 / 74
Two vectors of equal magnitude V with angle 60° to each other. The magnitude of their resultant is:
R = √(V² + V² + 2·V·V·cos 60°) = √(2V² + 2V²·½) = √(2V² + V²) = √(3V²) = V√3
51 / 74
If A = 7î + 24ĵ, the magnitude of A is:
|A| = √(7² + 24²) = √(49 + 576) = √625 = 25.
52 / 74
Two equal forces P each act at a point with an angle of 120° between them. The magnitude of their resultant is:
We know:cos(120°) = -1/2
So,R = √[2P² + 2P²·(-1/2)]R = √[2P² – P²]R = √[P²]R = P
53 / 74
If the sum of two unit vectors is a unit vector, then the magnitude of their difference and the angle between them are, respectively:
Let the two unit vectors be A and B.So,|A| = |B| = 1|A + B| = 1
Use the formula:|A + B|² = |A|² + |B|² + 2|A||B|cosθ
⇒ 1² = 1² + 1² + 2(1)(1)cosθ⇒ 1 = 1 + 1 + 2cosθ⇒ 1 = 2 + 2cosθ⇒ 2cosθ = -1⇒ cosθ = -1/2⇒ θ = 120°
Now, find |A − B|:|A − B|² = |A|² + |B|² − 2|A||B|cosθ= 1 + 1 − 2(1)(1)(cos120°)= 2 − 2(−1/2)= 2 + 1 = 3⇒ |A − B| = √3
54 / 74
At what angle should the two force vectors 5 N and 12 N be added to get a resultant of 13 N?
For resultant we use below formula:
55 / 74
Two equal forces F act at right angles on a point. The magnitude of their resultant is:
56 / 74
A particle moves 5 m east then 12 m north. Its resultant displacement from the start is:
57 / 74
The angle between vector Q and the resultant of (2Q + 2P) and (2Q – 2P)
(2Q + 2P) + (2Q – 2P) = 4Q, which is parallel to Q, so the angle between them is 0°.
58 / 74
Two perpendicular forces have magnitudes A and A/2. The magnitude of their resultant is:
59 / 74
When A = 2î + 3ĵ + 2k̂ is subtracted from B, the result is 2ĵ. The magnitude of B is:
B – A = 2ĵ ⇒ B = A + 2ĵ = 2î + (3+2)ĵ + 2k̂ = 2î + 5ĵ + 2k̂ ⇒ |B| = √(4+25+4) = √33.
60 / 74
A vector in the xy-plane makes an angle of 30° with the y-axis. Its y-component is 2√3. The magnitude of its x-component is:
61 / 74
Given A = (2, 3) and B = (–2, –3), the graphical sum A + B forms:
Plot A, then attach B head-to-tail; you return to the origin.
A and B are equal in magnitude but opposite in direction.
Their head-to-tail connection completes the path back to the start, you will get a straight line.
62 / 74
Which property of vector addition states A + B = B + A?
“Commutative” means order doesn’t matter.
Graphically, placing A then B, or B then A, yields the same head-to-tail resultant.
Magnitude and direction are identical either way.
This holds for all vectors in a vector space.
63 / 74
Which is not part of adding vectors by rectangular components?
Steps: (1) resolve into components, (2) add all x’s and all y’s, (3) recombine into R.
Parallelogram law is an equivalent graphical check.
At no point do you multiply components.
Option (d) is irrelevant to vector addition.
64 / 74
Two vectors A and B add to a resultant purely along the x-axis if:
Pure x-axis resultant means no net vertical component.
Component addition: Rᵧ = Aᵧ + Bᵧ must be zero.
Horizontal sum Aₓ + Bₓ can be nonzero.
Hence only condition (a) guarantees R is along x.
65 / 74
If A = 8î + 6ĵ and B = –8î + 6ĵ, the resultant A + B lies:
Sum x-components: 8 + (–8) = 0 → no horizontal part.
Sum y-components: 6 + 6 = 12 → positive vertical part.
Zero x and positive y ⇒ a vector straight up along +y.
66 / 74
Which method adds two vectors by drawing them from the same origin to form a parallelogram?
Parallelogram law uses the two vectors as adjacent sides.
The diagonal from the common origin is the resultant.
It decomposes into perpendicular components on x and y.
This visual proof also shows commutativity of addition.
67 / 74
A = 4î + 3ĵ and B = –2î + 6ĵ. What is the angle θ of R from the +x-axis?
Rₓ = 4 + (–2) Rₓ = 2, Ry = 3 + 6 Ry = 9.
θ = tan⁻¹(Ry/Rx) = tan⁻¹(9/2).
Compute components first, then use tan⁻¹.
This yields the correct direction of R.
68 / 74
A = 3î – 4ĵ, B = –5î + 2ĵ. The resultant A + B is:
Sum x-components: 3 + (–5) = –2 → –2î.
Sum y-components: –4 + 2 = –2 → –2ĵ.
R = –2î + (–2ĵ) by component-wise addition.
Vector closure ensures the result is itself a vector.
69 / 74
If Ax+ Bx= 0 but Ay + By ≠ 0, then A + B
Zero x-sum means no horizontal part; nonzero y-sum gives a pure vertical resultant.
70 / 74
Two equal-magnitude vectors at right angles are added. The resultant’s magnitude is V√2 because
If each component= V, then R = Vî + Vĵ use Pythagoras’ theorem ⇒ |R| = √(V² + V²) = V√2.
71 / 74
A = 5î + 0ĵ and B = 0î + 12ĵ. The magnitude of A + B is
R = (5+0)î + (0+12)ĵ = 5î + 12ĵ. Magnitude = √(5² + 12²) = 13.
72 / 74
Subtracting 2î + 7ĵ from î + ĵ gives ______
Subtract component-wise: (î+ĵ) – (2î+7ĵ) = (1–2)î + (1–7)ĵX-component: 1 – 2 = –1 → –îY-component: 1 – 7 = –6 → –6ĵ Resultant: –î –6ĵ
73 / 74
ding 2î + 7ĵ and î + ĵ gives ______
Add x-components: 2 + 1 = 3Add y-components: 7 + 1 = 8Result: 3î + 8ĵ
74 / 74
On adding two vectors we get _____
On adding two vectors we get a vector. Vector addition preserves both magnitude and direction. Use the head-to-tail or parallelogram law to find the resultant. Vectors are closed under addition, so the result is always another vector.
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