A man generates a symmetrical pulse in a string by moving his hand up and down. At t = 0, the point in his hand moves downwards from mean position. The pulse travels with speed `3m//s` on the string and his hand passes 6 times in each second from the mean position. Then, the point on the string at a distance 3 m will reach its upper extreme first time at t =

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`.