Answer:
the distance between the ships is changing at 21.4 km/h
Step-by-step explanation:
Given;
distance between ship A and ship B = 150 km
speed of ship, A = 35 km/h
speed of ship B = 25 km/h
at 4 pm, the time difference = 4 hours
let the distance between A and B = C
The position of A after 4 hours = 35 km/h x 4 h = 140 km
The distance covered by A, a = 150 km - 140 km = 10 km
The distance covered by B, b = 25 km/h x 4 h = 100 km
The distance between A and B;
c² = a² + b²
c² = 10² + 100²
c² = 10100
c = √10100
c = 100.5 km
The change in the distance between A and B is calculated as;
[tex]c^2 = a^2 + b^2\\\\2c\frac{dc}{dt} = 2a\frac{da}{dt} + 2b\frac{db}{dt} \\\\c\frac{dc}{dt} = a\frac{da}{dt} + b\frac{db}{dt} \\\\100.5(\frac{dc}{dt}) = -10(35) + 100(25) \\\\(the \ negative \ sign \ indicates \ decrease \ in \ distance \ of \ A \ from \ B \ with \ time)\\\\100.5(\frac{dc}{dt})= 2150\\\\\frac{dc}{dt} = \frac{2150}{100.5} \\\\\frac{dc}{dt} = 21.39 \ km/h\\\\\frac{dc}{dt} \approx 21.4 \ km/h[/tex]
Therefore, the distance between the ships is changing at 21.4 km/h
