A transverse wave is travelling along as string from left to right, Fig. below represents the shape of the string at a given instant. Al this instant
(a) which points have an upward velocity?
(b) which points will have downward velocity ?
(c) which points have zero velocity ?
(d) which points have maximun 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