When the emergency warning siren at Cheryl's school was tested, the sound from the siren took 7.0 s to reach her house located 2.40 km from the school. What is the speed of sound in air ?
2007-06-25 15:16:16 · 8 answers · asked by Tam 1 in Science & Mathematics ➔ Physics
The equation for velocity (or speed if you ignore direction) is simply:
v = x / t, where x is distance and t is time. So, you have:
v = 2.40 km / 7.0 s
v = 2.40 km*(1000 m / 1 km) / 7.0 s
v = 2400 m / 7.0 s
v = 342.857 m/s
So, the speed of sound in air is roughly 343 m/s.
2007-06-25 15:21:22 · answer #1 · answered by C-Wryte 3 · 0⤊ 0⤋
Yes, it depends on temperature (and humidity and pressure and even wind speed -- anything that affects density). When air is cool, its molecules are not bouncing around as much, so they are more tightly packed -- that is, more dense. Therefore, sound is tranferred more quickly through them. Imagine a billiards table PACKED with balls, and one with balls spread out -- when you hit the balls on the packed table, a ball instantly pops out the other side. However, on the spread out one, it takes a while for the balls to hit each other and pop one off the other end. The packing of the air molecules depends on the kinetic energy they have, and that is measured by air temperature. Hot molecules are more excited and spread out, just like excited dancers on a dance floor.
2016-05-20 03:32:02 · answer #2 · answered by Anonymous · 0⤊ 0⤋
The time of the siren sound reach to the house in this case depends on the frequency of the siren. So it need a long time to be heard by HUMAN, but it CAN BE heard by other animal -like dog- with less time.
Bu in the general, the speed of sound in the air is 300.000 m/s.
2007-06-25 15:29:29 · answer #3 · answered by Arfianto M 2 · 0⤊ 1⤋
For the question at hand, it is 2.4km (2400m) / 7 or 342.86 m/s
However, the speed of sound does depend on altitude and temperature (or air density) for a more challenging question ,one could determine the air density at the time of the events in the question.
One common search engine (sorry Yahoo) says "speed of sound at sea level = 340.29 m / s", pretty close, but not exactly, the speed in this case.
2007-06-25 15:26:17 · answer #4 · answered by tinkertailorcandlestickmaker 7 · 0⤊ 0⤋
The speed of sound is a function of air density and temperature.
Air is a mixture of gases but we assume a constant composition of nitrogen, oxygen and some water vapor (humidity is a factor).
Approximately however
v= 331.4 + .6T m/s
where T is in degrees Centigrade.
However in your case
V=S/t= 2400m/7.0s=342.9 m/s
2007-06-25 15:31:55 · answer #5 · answered by Edward 7 · 0⤊ 0⤋
Speed = distance/time
Speed of sound = 2400m/7.0sec
Speed of sound in air = 343m/s
2007-06-25 15:22:10 · answer #6 · answered by Tsumego 5 · 0⤊ 0⤋
2.4 km x 1/7 sec x 3600 sec/hr = 1234.28 km/hr
2007-06-25 15:22:36 · answer #7 · answered by mechnginear 5 · 0⤊ 0⤋
2,400m ÷ 7 = 343m/s
2007-06-25 15:42:00 · answer #8 · answered by Norrie 7 · 0⤊ 0⤋