A student goes to the laboratory supply room and obtains five feet of clear plas

Question

A student goes to the laboratory supply room and obtains five feet of clear plastic tubing with an outer diameter of 1/2 inch and a wall thickness of 1/16 inch. She bends the tube into a U shape with the open ends pointing up and uses a funnel to pour 75 mL of water into the tube. By blowing air into one end of the tube, she generates a 6-inch difference in the water levels on each side. What was the pressure (atm) she exerted with her lungs on the water in the tube State all assumptions you make. If the fluid had been ethanol instead of water, what would the difference in the liquid levels have been

Explanation / Answer

Difference in water levels =6 inches =6/12 ft= 0.5ft =0.5*0.3048m =0.1524m

Negelctnig the density of air ( which is much less than the density of water)

Pressrue difference = 0.1524 m of water

but 1 atm =10.3m water

0.1524 m of water= 0.1524/10.3=0.014796 atm

Pressure exerted = atmospheric pressure =1+0.014796 atm =1.014796 atm

b) from (density of ethanol* height of ethanol)= density of water* height of water ( P= density*g*h)

0.78*h= 0.1524*1 h= 0.1724/0.78=0.195 m =0.64ft= 0.64*12inches= 7.68 inches

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