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## Practice – Physics – sounds

1. The water in the plumbing in a house is at a gauge pressure of 626 pounds per square foot. What force does this cause on the top of the tank inside a water heater if the area of the top is 2.15 square feet?

2. If a balloon is filled with 1000 m3 of helium (at 0 oC temperature and 1 Atm pressure). What is the mass of the helium?

[The density of helium is 0.18 kg/m3]

3. When a spigot is open, water emerges from a garden hose with a speed of 30 in/s.  If the garden hose has an opening with a cross-sectional area of 0.8 in2, what would be the speed of the water as it emerges from the hose if the area of the opening were reduced to 0.3 in2?

4. Ultrasound probes are used to resolve structural details within the human body. It is possible to resolve to about the dimension of the sound wavelength. The speed of sound within the body is 1540m/s. If a person is examined with a 25 MHz ultrasound probe what is the smallest detail that can be detected?

5. How far can a sound wave travel in 60 seconds when the ambient air temperature is -35 °C?