Multiple choice question.

[nil1996]

Homework Statement

In a standing wave on a string
(a)In one time period all the particles are simultaneously at rest.
(b)All the particles must be at their positive extremes simultaneously once in time period.
(c)All the particles may be at their positive extremes simultaneously once in time period.
(d)All the particles are never at rest simultaneously.

Homework Equations

concepts of waves

The Attempt at a Solution

(a) Yes it is true, at maximum positions all particles are at rest.

(b)This is only true for fundamental frequency of the standing waves, but that is not mentioned . So it is false

(c)This is where i am confused. This condition can only happen in fundamental frequency.But the particles are twice at their positive extremes.So i am not sure about it. One of books say that this is false while other says this is true.

(d)False

Please help me on the c option.

 

[CWatters]

But the particles are twice at their positive extremes

In one time period they are at the positive extreme once and the negative extreme once.

 

[nil1996]

oh,thanks