Two vectors have magnitudes 5 and 10, and their resultant is perpendicular to the vector of magnitude 5. Which pair gives the angle between the vectors and the resultant magnitude?
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Two vectors have magnitudes 5 and 10, and their resultant is perpendicular to the vector of magnitude 5. Which pair gives the angle between the vectors and the resultant magnitude?

G1 Physics · Accepted Answer

Perpendicular condition: 5+10cosθ=0 ⇒ cosθ=−1/2 ⇒ θ=120°. Then R²=25+100+100cos120°=75, so R=5√3.