What is the least amount of time required for a given point on this wave to move from y = 0 to y = 12cm?

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, 

t = 12/2

t = 6 sec

so 6 sec is the least amount of time required

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