If the two waves combine to produce ANY wave that smaller
than either of the originals, that's destructive interference.
<h2>The man have to apply force of 160 N</h2>
Explanation:
The work done to lift the bag of weight mg through height 2.5 m is 400 J
The work done can be found by relation W = mg x h
Thus mg =
=
= 160 N
Therefore the man have to apply the force of 160 N
The law of floatation states that, a floating body displaces its own weight of the fluid in which it floats.