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
EQUIPMENT FOR RESISTANCE WELDING-Measurements Measurement of the parameters are important while fixing the parameters or testing a machine. Resistance welding instrumentation s

what is Direct and Reverse crank method of balancing

hello,my name is mustapha from iran I want design piston engine (structure design cranckshaft ,rod,bearing,...)

Draw bending moment diagram: Draw the shear force diagram (SFD) & bending moment diagram (BMD) for the beam illustrated in Figure . Solution Reaction at the support A,

Wet saturated steam -  thermodynamics: we t saturated steam Wet steam is a 2-phase mixture comprising of boiling water particles and dry steam in equilibrium state. Its for

In general safety and service tips, you learnt about general service and safety tips those must be followed while working in workshop. It gives the competency statements useful for

Concentrate d or Point Load: How many types of load are acting on the beam? A beam is usually horizontal and the loads acting on beams are usually vertical. The followi

Q. Module Assembly Site Preparation? To set a module on the piles installed on project site, the following preparations shall be made: The Designer shall provide design elev


why this great equation does not apply(involved) in nuclear reaction ?