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Vector Algebra question

2023 · 15 Apr · Shift 1 · Q55
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  5. /2023 · 15 Apr · Shift 1 · Q55

Vector Algebra question

2023 · 15 Apr · Shift 1 · Q55

JEE MainPhysicsVector AlgebraMCQ+4 / −1
A vector in x−yx-yx−y plane makes an angle of 30∘30^{\circ}30∘ with yyy-axis. The magnitude of y\mathrm{y}y-component of vector is 232 \sqrt{3}23​. The magnitude of xxx-component of the vector will be :
  1. A
    3\sqrt{3}3​
  2. B
    2
  3. C
    6
  4. D
    13\frac{1}{\sqrt{3}}3​1​
View written solutionFree

Correct answer: B

  1. Let the vector have magnitude VVV and make an angle of 30∘30^\circ30∘ with the yyy-axis.

  2. Since the angle is given with the yyy-axis: ∣Vy∣=Vcos⁡30∘|V_y| = V\cos 30^\circ∣Vy​∣=Vcos30∘ and ∣Vx∣=Vsin⁡30∘|V_x| = V\sin 30^\circ∣Vx​∣=Vsin30∘

  3. Given: ∣Vy∣=23|V_y| = 2\sqrt{3}∣Vy​∣=23​ So, Vcos⁡30∘=23V\cos 30^\circ = 2\sqrt{3}Vcos30∘=23​

  4. Use cos⁡30∘=32\cos 30^\circ = \frac{\sqrt{3}}{2}cos30∘=23​​: V(32)=23V\left(\frac{\sqrt{3}}{2}\right) = 2\sqrt{3}V(23​​)=23​ V=23⋅23=4V = \frac{2\sqrt{3} \cdot 2}{\sqrt{3}} = 4V=3​23​⋅2​=4

  5. Now find the xxx-component: ∣Vx∣=Vsin⁡30∘=4(12)=2|V_x| = V\sin 30^\circ = 4\left(\frac{1}{2}\right) = 2∣Vx​∣=Vsin30∘=4(21​)=2

  6. Hence, the magnitude of the xxx-component is: 2\boxed{2}2​

  7. Checking options:

    • A: 3\sqrt{3}3​
    • B: 222 ✅
    • C: 666
    • D: 13\frac{1}{\sqrt{3}}3​1​

Therefore, the correct option is B.

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