Mechanical Engineering - Hydraulics and Fluid Mechanics - Discussion

Discussion Forum : Hydraulics and Fluid Mechanics - Section 2 (Q.No. 34)
34.
In a footstep bearing, if the speed of the shaft is doubled, then the torque required to overcome the viscous resistance will be
double
four times
eight times
sixteen times
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
8 comments Page 1 of 1.

Sham Malik said:   6 years ago
Formula for torque of foot step bearing is; mu*π^2*N*R^4/60t.

N doubled then T doubled.

Ajaygiri said:   6 years ago
T = ϲuNR^4/60t.

u - viscosity of the oil.
N - speed of the shaft.
R - radius of the shaft.
t - the thickness of the oil film.

And T proportional to N.

Rohit Koundal said:   7 years ago
Torque = π*N*u*R^4/60t.

Aamir said:   8 years ago
Apply formula of rotating cylinder viscometer, in which torque is directly pro to shaft speed.

Meet said:   8 years ago
Consider an annular strip of radius r and width dr.
F = Aμ (du/dy) = A μ(u/y)
u = 2πrN/60, y = h, A = 2πr dr y=h=clearance

Torque = Force * radius.
dT = 2πr dr μ(2πrN/60h)r.
dT proportional to N.

Raja raha said:   9 years ago
Formula:

T = pie^2*N*R^4/60t.

Shiva said:   1 decade ago
@Manoj.

No, Torque is directly proportional to speed both in journal and footstep bearing.

Manoj said:   1 decade ago
T inversely proportional to N(speed of shaft).

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