Solve the problem.
-Two recording devices are set 3,200 feet apart, with the device at point A to the west of the device at pointB. At a point on a line between the devices, 300 feet from point B, a small amount of explosive isdetonated. The recording devices record the time the sound reaches each one. How far directly north ofsite B should a second explosion be done so that the measured time difference recorded by the devices isthe same as that for the first detonation?
A)669.23 ft
B)4,886.38 ft
C)1,571.62 ft
D)1,479.14 ft

Question

Quizplus · Accepted Answer

The correct answer is A.The time difference between the two recordings is proportional to the difference in the distances from the explosion to the two recording devices. Since the recording devices are 3,200 feet apart and the explosion is 300 feet from point B, the difference in the distances is 3,200 - 300 = 2,900 feet.To get the same time difference, the second explosion should be placed at a point where the difference in the distances to the two recording devices is also 2,900 feet. Since the recording devices are 3,200 feet apart, the second explosion should be placed at a point that is 3,200 - 2,900 = 300 feet from point A.Since the second explosion is directly north of point B, the distance from the second explosion to point B is the same as the distance from the first explosion to point B, which is 300 feet. Therefore, the second explosion should be placed at a point that is 300 feet directly north of point B.

Solve the Problem. -Two Recording Devices Are Set 3,200 Feet Apart, with the Apart