Question

- A submarine is at a sea level at 8.00 pm. It begins to descend at a rate of 8 m per minute. (a) At what time will it reach -240 m?
(b) At that time, what is the distance between the submarine and the helicopter flying 960m above sea level?​

Answer 1

a) Distance covered per minute: 8m

   Distance covered in x time: -240m

  -240m divided by 8m= 30 minutes

Therefore at 8:30 pm the submarine reaches -240 metres

b) Take sea level as point O. The helicopter is flying at a vertical distance of 960m above O.  Meanwhile, the submarine is -240 m below O at that time. Therefore, add the distance between the helicopter and the sea level, and the distance between the submarine and the sea level. Or, in other words, 960m + (-240m). The answer is 720 m.

I'm sorry for answering a couple of hours after the exam, but I hope it helps Soumya!