Answer
Glenda will hear a splash $~~1.22~s~~$ after she releases the coin.
Work Step by Step
We can find the time it takes for the coin to fall 7.00 meters:
$\Delta y = \frac{1}{2}a_yt^2$
$t = \sqrt{\frac{2\Delta y}{a_y}}$
$t = \sqrt{\frac{(2)(7.00~m)}{9.80~m/s^2}}$
$t = 1.195~s$
We can find the time it takes for the sound to travel 7.00 meters:
$t = \frac{d}{v} = \frac{7.00~m}{343~m/s} = 0.0204~s$
The total time is $1.195~s+0.0204~s = 1.22~s$
Glenda will hear a splash $~~1.22~s~~$ after she releases the coin.
