When you open the valve on your garden hose, with the hose full of water, a pressure wave travels along the hose at the speed of sound in water (water level in reservoir comes down, when these pressure waves reaches reservoir ).

-Reference -- Fundamentals of Physics by Halliday, Resnick, Walker, Sixth Edition, Page No. 617

Question: When, where, who, how the above statement has been experimentally verified ? (Please concentrate on sentence "when you OPEN the valve". I am NOT talking about "when you CLOSE the valve".)

If we carry out experiment, we will find that water level in reservoir comes down instantaneously i.e. at exactly same moment we open the valve. Obviously faster than speed of light.

Thanks And Please Do Reply Me.

-Abhi. _________________________________________________ Abhijit Patil, C/o LIC of India, Shahada, Dist: Nandurbar, (MS), India. Pin: 425409. Email: xabhix@hotmail.com Homepage: http://www.geocities.com/discoverynews _________________________________________________

Perhaps the reason is that the speed of sound in water is about 1500 m/s. With a 15 m long hose the time-lag would only be 0.01s. Without a sophisticated measuring device this would seem instantanous.