A man gerates a symmetrical pulse in a strin by moving his hand up and down. At `t = 0` the point in his hand moves downward. The pulse travels with speed `3 m//s` on the string & his handsd pass `6` times in each second from the mean position. Then the point on the string t a distance `3m` will reach its upper extreme first at time `t = n//12`. Find `n`

Options

A. `1.25 sec`
B. 1 sec
C. `(11)/(12) sec`
D. none

Answer

A

Explanation

Frequency of wave `= (6)/(2)-3 rArr T=(1)/(3) s, lamda -vT=(3)((1)/(3))=1m`
Total time taken `= (3)/(3)+(3T)/(4)=1.25 sec`.