Solving Viscosity Problems in an Auto Lift

  • Thread starter Thread starter kp3legend
  • Start date Start date
  • Tags Tags
    Viscosity
AI Thread Summary
The discussion revolves around calculating the viscosity of oil in an auto lift system and the shear stress at the inner cylinder's surface. The user is attempting to determine the surface area of both the ram and the cylinder, questioning the accuracy of their calculations. They found the surface area for both to be approximately 4.89 m², which they believe shows no significant difference. The user calculated the viscosity to be around 1.4 kg/ms or 14 P but is uncertain about its correctness. Clarification on the calculations and methodology is sought to ensure accurate results for an upcoming presentation.
kp3legend
Messages
8
Reaction score
0

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.
 
Physics news on Phys.org
What is the surface area of the cylinder? What is the surface area of the ram? Is the difference really significant?
 
  • Like
Likes 1 person
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
 
Last edited:
That's what I get.
 
  • Like
Likes 1 person
thank you very much !
 
Thread 'Help with Time-Independent Perturbation Theory "Good" States Proof'

Thread 'Help with Time-Independent Perturbation Theory "Good" States Proof'

(Disclaimer: this is not a HW question. I am self-studying, and this felt like the type of question I've seen in this forum. If there is somewhere better for me to share this doubt, please let me know and I'll transfer it right away.) I am currently reviewing Chapter 7 of Introduction to QM by Griffiths. I have been stuck for an hour or so trying to understand the last paragraph of this proof (pls check the attached file). It claims that we can express Ψ_{γ}(0) as a linear combination of...
View full post »

Hot Threads

Recent Insights

Back
Top