Solving Viscosity Problems in an Auto Lift

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In summary, the conversation discusses an auto lift consisting of a ram and cylinder filled with viscous oil. The combined mass of the automobile, auto rack, and ram is given. The task is to determine the viscosity of the oil and the shear stress at the surface of the inner cylinder. The surface areas of both the cylinder and ram are found to be 4.89m^2, with no significant difference. The calculated viscosity is 1.4kg/ms or 14 P.
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kp3legend
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Homework Statement


An auto lift consists of a 55.56 cm diameter ram which slides concentrically in a 55.58 cm diameter
cylinder (see Figure 1). The cylinder engages a 2.8 m length of the ram at all times. The annular region
between the ram and cylinder is filled with viscous oil. The combined mass of the automobile, auto rack
and ram is 1750 kg. If the lift drops steadily at the speed of 0.25 m/s after being released, determine:
a) the viscosity of the oil, in Pa.s,
b) the shear stress at the surface of the inner cylinder.


Homework Equations



F=uA(v/y)
F=mg
t=u(du/dy)

The Attempt at a Solution



I can find the force which is the weight og ram+ram, also dy and dv. but i don't know how to find A. my friends told me that A = 2pi*2.8 put i don't think it was right because 2.8m is the length of the whole thing not diameter.
Please help me. I need to give my class a presentation about this and it counts as a test.
 
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  • #2
What is the surface area of the cylinder? What is the surface area of the ram? Is the difference really significant?
 
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  • #3
the surface of the cyclinder is 4.89m^2 and the surface area for the ram is also 4.89m^2. and no i don't see any huge differences between those values. and when i tried to find the viscosity it give me the value of 1.4kg/ms or 14 P. I don't know if mine is correct or not :( could you check for me please
 
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  • #4
That's what I get.
 
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  • #5
thank you very much !
 

Related to Solving Viscosity Problems in an Auto Lift

What is viscosity?

Viscosity is a measure of a fluid's resistance to flow. It is often described as the thickness or "stickiness" of a fluid.

Why is viscosity important in an auto lift?

In an auto lift, viscosity is important because it affects the performance and safety of the lift. Too high viscosity can cause the lift to operate slowly and put strain on the lifting mechanism, while too low viscosity can lead to instability and potential accidents.

How can I solve viscosity problems in an auto lift?

To solve viscosity problems in an auto lift, you can start by checking the manufacturer's recommendations for the type and viscosity of fluid to use. If the viscosity is too high, you may need to replace the fluid with a lower viscosity or add a viscosity reducer. If the viscosity is too low, you can add a viscosity enhancer or replace the fluid with a higher viscosity.

What are common causes of viscosity problems in an auto lift?

Some common causes of viscosity problems in an auto lift include using the wrong type or grade of fluid, contamination of the fluid with debris or water, and lack of regular maintenance and fluid changes.

How often should I check and change the fluid in my auto lift?

It is recommended to check the fluid levels and condition in your auto lift at least once a month and change the fluid every 6 to 12 months, depending on the manufacturer's recommendations. Regular maintenance can help prevent viscosity problems and ensure the safe and efficient operation of your auto lift.

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