# physics!

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A torpedo fired from a submerged submarine is propelled through the water with a speed of 20.00 m/s and explodes upon impact with a target 2000.0m away. If the sound of the impact is heard 101.4s after the torpedo was fired, what is the speed of sound in water?

(becuz the torpedo is held at a constant speed by its propeller, the effect of water resistance can be neglected)

• physics! -

Isn't this just
distance = rate*time?
2000 = 20*time , solve for time,
t = 2000/20 = 100 seconds is how long it took the torpedo to get to the target.
It took 101.4 seconds after the torpedo was fired to hear the sound and 100 seconds was required for the torpedo to make the trip to the target; therefore, it took 1.4 seconds for the sound to get back to the submarine.
2000 = r*(1.4). Solve for rate.
I get about 1,500 or so. See here for the speed of sound in water. Check my thinking. Check my work.
http://en.wikipedia.org/wiki/Speed_of_sound#water

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