Mechanism with 2 Sliders: Angular Acceleration of Rod?

[NEILS BOHR]

FIITJEE OPEN TEST question...

Homework Statement

A mechanism with 2 sliders is shown in the fig. Slider A at the instant shown has a speed of 3 m/sec and is accelerating at the rate of 15 m/s^2 towards rite at the given instant . If rod AB has a length of 3m and $$\theta$$ is 60 degree at the instant shown. Find angular acceleration of the rod.

http://img710.imageshack.us/i/82051883.png/

Homework Equations

The Attempt at a Solution

i have found the angullar velocity of end B...but can't proceed further!

 

[graphene]

What do you think is the velocity of A ?

 

[NEILS BOHR]

velocity of end A is given/...

 

[graphene]

Oops, I meant end B.

 

[NEILS BOHR]

i have calculated vel of B as 3 m/s..

 

[gneill]

Homework Statement

A mechanism with 2 sliders is shown in the fig. Slider A at the instant shown has a speed of 3 m/sec and is accelerating at the rate of 15 m/s^2 towards rite at the given instant . If rod AB has a length of 3m and $$\theta$$ is 60 degree at the instant shown. Find angular acceleration of the rod.

http://img710.imageshack.us/i/82051883.png/

Your image shows two angles designated $$\theta$$. Which is which? And what is R = 3m? The radius of the curved track?

 

[NEILS BOHR]

ya the r is radius of curved path...

and the theta is the angle which rod makes with horizontal...

 

[gneill]

ya the r is radius of curved path...

and the theta is the angle which rod makes with horizontal...

So, the angle designated theta at the center of curvature of the curved path is spurious? Is the actual angle unknown, or does the diagram imply that path radius and rod form a straight angle (180 degrees) at the instant in question? This would fix the distance of the horizontal path from the center of curvature of the curved path.

 

[graphene]

if you can find the acceleration of end B, you should be able to find the angular acceleration of the rod.

 

[gneill]

if you can find the acceleration of end B, you should be able to find the angular acceleration of the rod.

While that is no doubt true, it is also true that if the acceleration depends upon the geometry of the mechanism, then the specific layout at the instant in question would be important. Having a straight angle between A and the path center presents a different situation than if the line AB does not intersect the that center.

 

[NEILS BOHR]

@graphene
how??can u pleasez give a hint or somethin?

 

[NEILS BOHR]

more replies pleasezz

 

[gneill]

more replies pleasezz

Show some of your work so far! What's your approach?

 

[NEILS BOHR]

well i told you i found out the vel. of end B but then i m confused how to find angular acc..
i tried using IAOR but cudnt reach there...