# Physics problem echoes

1. Jan 15, 2017

### bilalsyed25

The Question:
A boat is floating at rest in dense fog near a large cliff. The captain sounds a horn at water level and the sound travels through the salt water (1470 m/s) and the air (340 m/s) simultaneously. The echo in the water takes 0.40s to return. How much additional time will it take the echo in the air to return?

Relevent equations: v=d/t

d = v∆t

d = 1470*0.40

d = 588/2 (I checked online for this question, some ppl got different answers due to this part; 558/2 or just 588?)

d = 294m

294/340 = 0.86s

0.86-0.40 = 0.46

2. Jan 15, 2017

### Staff: Mentor

Realize that the sound must travel to the cliff and back.

3. Jan 15, 2017

### PeroK

If something takes $0.4s$ to cover a distance and something else takes an extra $0.46s$ to cover the same distance, then the faster thing must be moving approx twice as fast as the slower thing. Is $1,470m/s$ approx twice $340 m/s$?