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The position co-ordinates of a particle moving in a 3-D coordinate system is given by x = a cosωt, y = a sinωt and z = aωt. The speed of the particle is:

1. aω
2. √3 aω
3. √2 aω
4. 2aω

Correct answer: √2 aω

Solution

vx=-a*w*sin(wt), vy=a*w*cos(wt), vz=a*w. Speed = sqrt(a^2 w^2 (sin^2+cos^2) + a^2 w^2) = sqrt(2) * a * w.

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