A transverse wave is traelling along a string from left to right. The fig. represents the shape of the string (snap-shot) at a given instant. At this instant

(A) Which points have an upward velocity , (B) which points have downward velocity
(C) which point have zero velocity , (D) which point have maximum magnitude of velocity.

Explanation

For a wave `v_(p) = -vxx`(slope) i.e., particle velocity is proportional to the negative of the slope of y/x curve, so
(a) For upward velocity `v_(p)`. is positive, so slope must be negative which is at points D, E and F.
(b) For downward velocity `v_(p)` is negative, so slope must be positive which is at A, B and H.

For zero velocity slope must be zero which is at Cand G.
(d) For maximum magnitude of velocity, slope = maximum which is at A and E