4ms I'm just guessing by the way
Answer:
The time elapses until the boat is first at the trough of a wave is 4.46 seconds.
Explanation:
Speed of the wave, v = 59 km/h = 16.38 m/s
Wavelength of the wave, 
If f is the frequency of the wave. The frequency of a wave is given by :

The time period of the wave is given by :

We need to find the time elapses until the boat is first at the trough of a wave. So, the time will be half of the time period of the wave.

Hence, this is the required solution.
Use conservation of momentum ;
m1u1 + m2u2 = m1v1 + m2v2
1200×15.6 + 0 = 2700v
v = 18720/2700
v = 6.933 or ~ 7 m/s
Hello!
For the explanation of this energy conservation exercise, where we'll use <u>energy conservation law</u>, let's see what this principle proposes.
How you should know, mechanical energy conserves in every point, that is to say mechanical energy is same in A point like B point. (Mechanical energy will be represented by "Me")
Once time we know that, let's take the 220 Joules momentum like A point, and when 55 Joules momentum like B point.
Then, let's use the <u>energy conservation principle:</u>
Me(A) = Me(B)
- We know Mechanical energy in A point, so just lets replace according to our data:
220 J = Me(B)
- In B point, we know kinetic energy, but <u>we dont know gravitational potential energy</u>, so lets descompose Mechanical energy, into kinetic energy and gravitational potential energy:
220 J = Ke + Gpe
- We know kinetic energy value, so lets replace it:
220 J = 55 J + Gpe
- Finally, just clean Gpe and resolve it:
Gpe = 220 J - 55 J = 165 J
Gravitational potential energy is of One hundred sixty five Joules <u>(165 J).</u>
║Sincerely, ChizuruChan║