If it takes the swing 2 seconds to complete one cycle, then
that's the period of its motion ... 2 seconds.
The frequency is the reciprocal of the period ... 1/2 Hz.
('Hz' means 'per second'.)
Answer:
yes this is truly the wrong answer
Take the stone's position at ground level to be the origin, and the downward direction to be negative. Then its position in the air 
at time 
is given by
Let 
be the depth of the well. The stone hits the bottom of the well after 5.00 s, so that
Your answer is A, Ocean Waves- because A mechanical wave is a wave that is an oscillation of matter, and therefore transfers energy through a medium. Ocean waves do just that :)
Hope this helps!!
