The resultant of two vectors P⃗ and Q⃗ is perpendicular to P⃗. If P=3 and Q=6, find the resultant magnitude.
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Question

The resultant of two vectors P⃗ and Q⃗ is perpendicular to P⃗. If P=3 and Q=6, find the resultant magnitude.

G1 Physics · Accepted Answer

P+Q cosθ=0 ⇒ cosθ=−1/2. Then R²=3²+6²+2(3)(6)(−1/2)=27, so R=3√3.