Submarine a and submarine b are heading
towards each other. they are both moving at a
steady speed of 5mls. submarine a produces
a pulse of sound to detect submarine b. the
sound is produced when the distance between
the two submarines was exactly 10 km.
the speed of sound in water is 1500 mls.
calculate the distance between submarine a
and submarine b when submarine a recieves
the echo reflected by submarine b.

The distance between the submarine is, d = 9933.3 m

Explanation:

Given data,

The speed of the submarine A and B, v  = 5 m/s

Submarine A produces  a pulse of sound to detect B at a distance, d = 10 km

                                                                                                          = 10000 m

The speed of sound in water is, V = 1500 m/s

The time period to receive echo is given by the formula,

                                                      t = d / v

                                                        = 10000 / 1500

                                                        = 6.67 s

The distance between the submarine is given by the relation

                                                    d = 10000 - 2(v x t)

                                                       = 10000 - 2(5 x 6.67)

                                                       = 9933.3 m

Hence, the distance between the submarine is, d = 9933.3 m

object 2 because all the other ones are wrong