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Hi Peter, Viscosity is a very important parameter in fluids. In most machines using fluids, a change in viscosity would have disastrous effects on the machine. Imagine what would happen if the gasoline in your car became as viscous as grease. The engine wouldnt be able to spray it and as a result the car wont run. Coming to your specific question, I cannot think of any practical application of your experiment. Thats because, the time an object takes to fall, is not dependant on its density at all. In fact it is only dependant on the distance it has to travel (s)(which is constant in your case), and the initial (u) speed and acceleration. The formula to be used is, s=ut + 0.5 at*t This does not have any relationship with density. Now, if you are getting different time intervals for objects of different densities, it could well be due to the fact that you are using objects which have different sizes (dimensions). What you could do is a slight change in plans. You could, using Stokes law calculate the viscosity of a fluid. Its called the falling sphere resistance method. The formula for the experiment is: F = 3*22/7*Mu*U*d where F is the force acting on the sphere Mu is the viscosity of the liquid U is the velocity of the sphere d is the diameter of the sphere d can be directly measured using a vernier calliper or a screw gauge (for more accuracy). U can be measured by noting the time(t) it takes for the sphere (ball) to fall the entire length (l) of the tube (U=l/t). F would be the weight of the sphere less the bouyant force. Bouyant force is the weight of the fluid displaced, which is the volume of the fluid displaced * the density of the fluid. Hope this helps. Best of luck Nauzad Tantra

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