Answer
given,
time = 10 s
ship's speed = 5 Km/h
F = m a
a is the acceleration and m is mass.
In the first case
F₁=m x a₁
where a₁ = difference in velocity / time
F₁ is constant acceleration is also a constant.
Δv₁ = 5 x 0.278
Δv₁ = 1.39 m/s

a₁ = 0.139 m/s²
F₂ =m x a₂
F₃ = F₂ + F₁
Δv₃ = 19 x 0.278
Δv₃ = 5.282 m/s
a₃=Δv₂ / t

a₃ = 0.5282 m²/s
m a₃=m a₁ + m a₂
a₃ = a₂ + a₁
0.5282 = a₂ + 0.139
a₂=0.3892 m²/s
F₂ = m x 0.3892...........(1)
F₁ = m x 0.139...............(2)
F₂/F₁
ratio = 
ratio = 2.8
In order to calculate the angle, we can use the formula below for a constructive interference (the interference is constructive because the fringe is bright):

Where d is the distance between the slits, m is the order of the interference and lambda is the wavelength.
So, using d = 8.25 * 10^-5, m = 2 and lambda = 4.5 * 10^-7, we have:

Therefore the correct option is the second one.
Is the variable you change, independent, I, something I change.
As per above given data
initial velocity = 19.3 km/s
final velocity = - 18.8 km/s
now in order to find the change in velocity




Part b)
Now we need to find acceleration
acceleration is given by formula

given that


now the acceleration is given as


so above is the acceleration