Most likely it would dislodge the coconut on the way down due to gravity because on the way up the gravity would slow down the rock but on they down the gravity pulls the rock
It will sink because mass does not affect the physical properties of the object.
Power= current*voltage or P=IV
so 16 watts=I*7 volts
divide on both sides to isolate I so you get
I= 16/7 which is about 2.3 amps
