    Question

# In a two - dimensional motion of a particle, the particle moves from point A, with position vector →[r1], to point B, with position vector →r2. If the magnitudes of these vectors are , respectively, r1=3 and r2=4 and the angles they make with the x - axis are θ1=75o and θ2=15o respectively, then find the magnitude of the displacement vector. A
15
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B
13
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C
17
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D
15
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Solution

## The correct option is B √13Given that, r1=3 r2=4 θ1=750 θ2=150 By cosine rule z2=r21+r22−2r1r2cos(θ1−θ2) z2=(3)2+(4)2−2×3×4cos600 z2=9+16−12 z=√13 Hence, the magnitude of the displacement vector is √13  Suggest Corrections  0      Similar questions  Related Videos   Motion Under Variable Acceleration
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