Explanation:
A) use the formula:

B) use the formula:

with angular velocity u calculated in A)
Answer: 5Hz
Explanation: Frequency = Wave speed divided by wavelength.
The sun radiates a lot of things we need like vitamin D and heat. It also is the energy source of organisms that survive off of photosynthesis, like plants, which we or other consumers eat.
It's like this:
Sun--->Producers (Plants and Protists) ---> Consumers (animals and humans) ---> Decomposers (mostly bugs, bacteria, and fungi)
Suppose rowing speed is V km/s.
So, upstream speed = V-2
Downstream speed = V+ 2
Total time is taken 3 h 20 min to cover up and down journey of 5 km.
So, total time = upstream time + downstream time


and
, we take only positive velocity.
Thus, the the rowing speed of the crew in still water is 1 km/s.