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Old Sep 28th 2019, 04:25 AM   #1
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What is the normal force in A and B?

What is the normal force in A and B?-skaermavbild-2019-09-27-kl.-12.20.59.png

A welded square frame consisting of four equal rods each with mass m and length 2l can move in the vertical plane by means of two small wheels in A and B that move frictionally along a horizontal or vertical track, respectively. The disc is released from rest in a position where the sides of the frame are horizontal and vertical respectively. Determine the normal forces in A and B at the beginning moment.

My attempt:


What is the normal force in A and B?-9a2171cd-4af8-4046-9238-aad500abfbf5_img-0389.jpg
What is the normal force in A and B?-img_0390.jpg
I have written on swedish but i think it will be quite easy to understand. As you can see if you watch my solution i get the wrong answer even though i feel like i am doing everything correct. The reaction force in B should be 6/5*mg, where as my answer is 3/10*mg.

Last edited by johanspeed; Sep 28th 2019 at 07:58 AM.
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Old Sep 29th 2019, 09:53 AM   #2
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I guess that the only source of force is gravity, which is moving in the ey direction.

At any time after the start time,
there will be lateral forces caused by the geometry.

But at the beginning time the only forces will be in the ey direction,
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Old Sep 30th 2019, 02:18 AM   #3
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Originally Posted by johanspeed View Post
Actually i solved it but i dont know how to mark this thread as solved or remove it
Can you please post your answer, just for those who read your thread and are curious?
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force, force and acceleration, normal, reaction, relative motion



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