Answer :
Time t = ?
When wave is moving from y = 0 to y =12 cm
By using the formula,
y = 15cos [(π/12) t)] = 0,
cos [(π/12) t)] = 0 = cos (π/2), so,
(π/12)t = π/2,t = (π/2) (12/π)
t = 12/2
t = 6 sec
so 6 sec is the least amount of time required
Time t = ?
When wave is moving from y = 0 to y =12 cm
By using the formula,
y = 15cos [(π/12) t)] = 0,
cos [(π/12) t)] = 0 = cos (π/2), so,
(π/12)t = π/2,t = 12/2
t = 6 sec
so 6 sec is the least amount of time required