Thursday, September 1, 2011

Fluid Statics Lab

the purpose of this lab was to see the different types of ways that one can measure buoyant force and how buoyant force is related to weight and tension 


first we tested the amount of buoyant force by tension and weight of the metal object, after calibrating the weight of the metal object above water was about 1.962 N +_ .05 N; after the object has fully submerged underwater the reading of the objects weight was about 1.75 N +_ .2 N


we can say that the tension plus the buoyant force should be equal to the weight of the object
                                                           W = T + B


with that comes out to B = .21 N +_ .05 N




we then measured the weight of an empty beaker and when it was filled with water, this gives us the mass of the beaker, water and the combination of the two.  




beaker weight .0995 kg +_ .005 kg
water weight .7375 kg +_.05kg
combination  weight .837 +_.06kg


from this we can calculate the weight of the displaced water and this should be equal to the buoyant force B
which is about .19 N +_ .05N


the volume method 


volume of the cylinder is given by the eq 
                                                                        pir^2h


we can use the vernier caliper to measured the radius and height of of cylinder 
r .019 m +_ .002m
h .045m +_ .005m


from that we can found out the volume of the cylinder and with the weight of the displaced water and the density of the water 1*10^3
we get that the displaced water weight should be something close to the buoyant force about .19 N


analysis 


the three values were quite close to one and another i would assume so because if the experiment was done with 100% precision then the value of B should be the same in all three experiments, but since that can be never achieved, approximation is all we can get, which quite good in this case. 


the weight sensor has to be the most accurate way, there are a lot less uncertainties to worry about ie spills of water out of the cup, estimation of length and radius of some equipment, and the computer software logger pro can take data for every .1 second maybe even less where as human can only do so every couple of seconds


if in the weight sensor experiment the metal cylinder was touching the bottom of the water container this would have changed the reading of B much greater, cause if the object is sitting or even just touching it would reduce the amount of tension that the spring is giving, you would expect the values of B to go up.

No comments:

Post a Comment