Coefficients of friction, Mechanical Engineering

Coefficients of friction:

The coefficients of friction under the sliding supports of the door in Figure are equal to 0.30 at A and 0.20 at B. What forces P shall give the 25 kg door a left ward acceleration of 3 m/sec2.

 Solution

The force, that means actions and reactions acting on the door are marked in Free Body Diagram. After showing the position and direction of inertia force on the body, we may write equilibrium equations as below :

∑ FX= 0, + P - X A - X B - 25 a = 0

∑ FY= 0, + YA + YB - 25 g = 0

∑ M CG = 0

YA × 1.2 + X A × 1.8 - YB × 1.2 + X B × 1.8 + P × 0.6 = 0

Also we have

X A  = 0.3 YA

X B  = 0.2 YB

And     a = 3 m / sec 2

∴ P = 0.3 YA  + 0.2 YB  + 75               ------------ (1)

and,   1.74 YA  - 0.84 YB  + 0.6 P = 0       ------- (2)

∴ 0.6 P = - 1.74 YA  + 0.84 YB

∴ P =- 2.90 YA  + 1.4 YB         ---------- (3)

Comparing Eqs. (1) and (3), we get

P = 0.3 YA  + 0.2 YB  + 75 = - 2.90 YA  + 1.4 YB

 ∴ 3.2 YA  - 1.2 YB  = - 75           --------- (4)

Also we have (from Σ Fy = 0) :

YA  + YB  = 25 × g

= 245.25                     -------- (5)

After solving Eqs. (4) and (5), we obtain

YB  = 195.41 N

∴ YA  = 49.84 N

And P = 129.04 N

Posted Date: 1/29/2013 2:52:03 AM | Location : United States







Related Discussions:- Coefficients of friction, Assignment Help, Ask Question on Coefficients of friction, Get Answer, Expert's Help, Coefficients of friction Discussions

Write discussion on Coefficients of friction
Your posts are moderated
Related Questions
steam boilar

Evaluate the tension in the rope: Determine the tension in the rope. Solution KE of the free-body of flywheel is developed due to (i) work-done by tension T in the rop

Is it possible for the steady state temperature profile in a plane wall to be nonlinear at steady state? If yes, provide one example. Solution: Steady state temperature profile

c programms fpr cycloidal motion

Example of simple exponential smoothing: A TV manufacturer utilizes simple exponential smoothing with α = 0.1 to forecast demand. For the first week of March, the forecast was

The following form basis of evaluation : The unit has obtained all necessary clearances whether statutory or administrative, e.g. drug license under drug control order, NOC

Determine the springs needed to absorb the energy: A vehicle weighing 28 kN and running at 2.5 m/sec is to be brought to rest by a buffer springs. Determine the number of spri

Q. Show Geographic constraints of the plant? The layout of process units will be influenced by the geographic constraints of the site. Spacing is required between plant facilit


Exhaust Manifold : The pipe which connects the exhaust system to the exhaust valve of the engine through which the products of combustion escape into the atmosphere is called the