A particle has position vector r = a cos(ωt)î + a sin(ωt)ĵ. Its velocity is:
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Question

A particle has position vector r = a cos(ωt)î + a sin(ωt)ĵ. Its velocity is:

G1 Physics · Accepted Answer

Step 1 — Principle: For sinusoidal vector motion, differentiate position to obtain velocity and acceleration. Step 2 — Working: Differentiate to obtain v=-aωsin(ωt)î+aωcos(ωt)ĵ. Step 3 — Working: The dot product r·v=0; hence velocity is perpendicular to the position vector. Correct answer: D — perpendicular to its position vector.