Question

ou are writing a short adventure story for your English class. In your story, two submarines need to arrive at a place in the middle of the Atlantic Ocean at the same time. They start out at the same time from positions equally distant from the rendezvouspoint. They travel at different speeds, but both go in a straight line. The first submarine travels at an average speed of 20 km/hr for the first 500 km, 40 km/hr for the next 500 km, 30 km/hr for the next 500 km and 50 km/hr for the final 500 km. In the story’s plot, the second submarine is required to travel at a constant velocity, so the captain needs to determine the magnitude of that velocity. What is that velocity?

Answer 1

Answer:

The constant speed of second submarine is 31.16 km/hr

Explanation:

Given that

v₁=20 km/hr ,d₁= 500 Km

v₂=40 km/hr ,d₂=500 km

v₃=30 km/hr, d₃=500 km

v₄=50 km/hr ,d₄=500 km

We know that

Displacement = Velocity x Time

d = v t

Total displacement = Average velocity x Total time

$d_1+d_2+d_3+d_4=V_{avg}\left(\dfrac{d_1}{v_1}+\dfrac{d_2}{v_2}+\dfrac{d_3}{v_3}+\dfrac{d_4}{v_4}\right)$

Now by putting the values

$2000=V_{avg}\left(\dfrac{500}{20}+\dfrac{500}{40}+\dfrac{500}{30}+\dfrac{500}{50}\right)$

$V_{avg}=31.16\ km/hr$

So the constant speed of second submarine will be the average speed of first submarine because they have to meet at the same time.

The constant speed of second submarine is 31.16 km/hr