Please help me UNDERSTAND this! I'm lost and I tried reading the book, but it doesn't explain it well. Thanks a lot!
A spherical balloon has a radius of 7.00 m and is filled with helium (density=.179 kg/m^3). Assume the skin and structure of the balloon have a mass of 931 kg. a) Find the buoyant force exerted by air (density=1.29 kg/m^3) on the balloon. b) If the balloon is tethered to the ground with a cord, find the tension in the cord.
A spherical balloon has a radius of 7.00 m and is filled with helium (density=.179 kg/m^3). Assume the skin and structure of the balloon have a mass of 931 kg. a) Find the buoyant force exerted by air (density=1.29 kg/m^3) on the balloon. b) If the balloon is tethered to the ground with a cord, find the tension in the cord.
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Buoyant force = V . rho . g = 4/3 . π . R^3 . 1.29 . 9.8 = 18163 N
Gravity force on the ballon = 4/3 . π . 7^3 . 0.179 . 9.8 + 931 . 9.8 = 11644 N
Tension = Upthrust – gravity force = 6519 N
Hi Texas... I have no idea how I got the number I did. I even checked it when it didn't agree with yours. I can only think that I managed to push the same wrong button twice and was unlucky enough to get a answer that was in the correct range and didn't question it further. Sorry.
Have checked the second number and that is correct and so the tension should now be correct.
Are you saying that 18163 N is being marked as incorrect? It should really be 18200 N ( and the tension should be 6520 N ) since all results should be to 3 significant figures... thats all I cna think off, unless the answer supplied is incorrect... which I have just been shown, is easy enough....
Cheers.
Rex
Gravity force on the ballon = 4/3 . π . 7^3 . 0.179 . 9.8 + 931 . 9.8 = 11644 N
Tension = Upthrust – gravity force = 6519 N
Hi Texas... I have no idea how I got the number I did. I even checked it when it didn't agree with yours. I can only think that I managed to push the same wrong button twice and was unlucky enough to get a answer that was in the correct range and didn't question it further. Sorry.
Have checked the second number and that is correct and so the tension should now be correct.
Are you saying that 18163 N is being marked as incorrect? It should really be 18200 N ( and the tension should be 6520 N ) since all results should be to 3 significant figures... thats all I cna think off, unless the answer supplied is incorrect... which I have just been shown, is easy enough....
Cheers.
Rex