Month: July 2012

Angular Displacement – 2011 A-level question

A disc rotates clockwise about its centre O until point P has moved to point Q, such that OP equals the length of the straight line PQ. What is the angular displacement of OQ relative to OP?

A.   $\frac{\pi}{3}$ rad

B.   $\frac{2\pi}{3}$ rad

C.   $\frac{4\pi}{3}$ rad

D.   $\frac{5\pi}{3}$ rad

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Answer: D.

The triangle OPQ is equilateral, so the angle $\angle QOP$ = 60° or $\dfrac{2\pi}{6}=\dfrac{\pi}{3}$ rad.

As OQ is displaced clockwise from OP, angular displacement $\theta = 2\pi – \dfrac{\pi}{3} = \dfrac{5\pi}{3}$ rad.

Static Electricity

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This question is meant for TA 2B and 2C Physics students.

Other than the demonstrations we have tried out during class, could you think of any other way in which static electricity can be observed?

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