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PhysicsNoob88

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**Need Help regarding some problems....**

Hi,

I have been trying to get these problems for some time now however at no prevail. If you guys can answer the questions below I promise I won't ever borther you guys again. Thanks a lot for those who do choose to help :shy:

1. The boat in the figure below has a weight (W) of 1400 N and floats at a depth of 8 m. The area of the hull is 60 m2.

(a) What is the weight density of the sea water in which it is floating ?

HINT : Consider the flotation principle

Rearranging the equation BF = WD x Volume,

WD = BF / volume ; volume = area x depth

(b) At what depth will the boat float if a 600 N cargo is added ?

HINT: Consider the flotation principle

Rearranging the equation BF = WD x Volume,

volume = BF / WD; and volume = area x depth

rearranging equation : depth = volume / area

2. Consider the hydraulic system below :

area in = 5 m2 ; area out = 80 m2

If a weight of 1600 N (Fout) must be lifted, how much force (Fin) must be applied to the input end ?

HINT - First determine what pressure must be provided at the output end to lift the weight of 1600 N.

3. A hot air balloon, with a mass of 14 kg., hoovers at an altitude of 8 km. where the weight density of the air is 2.8 N/m3. If a suitcase is dropped from the balloon, the balloon rises to an altitude where the weight density of the air is 2.1 N/m3. What is the weight of the suitcase ?

HINT: First determine the volume of the balloon; i.e., volume = BF / WD ; 'BF' is not 'mass'

Then using BF = WD x Volume, determine the new BF which can be used to determine the weight of the suitcase (i.e., this new BF is not equal to the weight of the suitcase)