Be easy-going and be yourself.
Answer:
39.240 W
Explanation:
Let's start by calculating the work done by the engine. We can assume that it is the same work done by the weight of the object to bring it from 40m to the surface: as much energy it takes to bring it up, the same ammount it takes to bring it down. Said work is 
At this point we can simply apply the definition of power, that is
, to get the power of the engine is 
Combination or composition, in particular.
I believe it goes as the following::
1) Waves transfer energy without moving particles
2) The two types of waves are longitudinal and transverse waves OR The two types of waves are mechanical and electromagnetic waves. Both are applicable and should be correct!