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TrojanPoem
 one year ago
Statics:
A metal homogeneous opaque ball with radius r was fastened from a point on its surface with a robe and the other end was fastened on point (A) on a rough vertical wall, the ball stationed in balance and It was about to slip down the wall at point (B). If AB = sqrt(3) r and the friction coefficient between the ball and wall is 1/sqrt(3).Prove that the tan of the angle which the robe makes with the wall is sqrt(3)/2 notice that the the action line of the ball weight affects on it's center.
TrojanPoem
 one year ago
Statics: A metal homogeneous opaque ball with radius r was fastened from a point on its surface with a robe and the other end was fastened on point (A) on a rough vertical wall, the ball stationed in balance and It was about to slip down the wall at point (B). If AB = sqrt(3) r and the friction coefficient between the ball and wall is 1/sqrt(3).Prove that the tan of the angle which the robe makes with the wall is sqrt(3)/2 notice that the the action line of the ball weight affects on it's center.

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dan815
 one year ago
Best ResponseYou've already chosen the best response.1what is the form for rotational intertia

dan815
 one year ago
Best ResponseYou've already chosen the best response.1you should have just drawn it :P

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1I though you'd prefer to draw it yourself :D

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1dw:1435161429650:dw

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1I can't add the lengths or the drawing will be nasty.

dan815
 one year ago
Best ResponseYou've already chosen the best response.1woah okay, this is confusing drawing

dan815
 one year ago
Best ResponseYou've already chosen the best response.1where is the horizontal wall?

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1Notice that : Fg = weight of the ball Fb = force of pulling in the robe m = friction coefficient r = reaction of the wall

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1typo not horizontal but vertical.

dan815
 one year ago
Best ResponseYou've already chosen the best response.1okay lemme try drawing it and see if i got this right

dan815
 one year ago
Best ResponseYou've already chosen the best response.1okay so our normal force is Fb* sin theta

dan815
 one year ago
Best ResponseYou've already chosen the best response.1did you say the resistance force are both from the frictional + moment of intertia

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1When the ball tries to slip , friction force will be generated = reaction of the wall x friction coefficient it's similar to this : dw:1435162343747:dw

dan815
 one year ago
Best ResponseYou've already chosen the best response.1yes u also have to account for the resistive interial force, trying to remmber how to apply that again

dan815
 one year ago
Best ResponseYou've already chosen the best response.1both of these will aid in lowering FB

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1You are getting it slowly.

dan815
 one year ago
Best ResponseYou've already chosen the best response.1just need the basic concept here like how do u find the resistive inertial force for a simpler question

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1dw:1435162643921:dw

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1mr + FBCosH = Fg , FBSinH = r

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1The moment at any point = 0

dan815
 one year ago
Best ResponseYou've already chosen the best response.1okk thats what i want, are u sure its just mr?

dan815
 one year ago
Best ResponseYou've already chosen the best response.1u have to add frictional force too there dont u

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1m = friction coefficient , r = reaction. Just those

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1maximum friction force = mr . So as to ease things I add mr directly.

dan815
 one year ago
Best ResponseYou've already chosen the best response.1reaction force is sintehta Fb

dan815
 one year ago
Best ResponseYou've already chosen the best response.1we need this part too thoughdw:1435162931881:dw

dan815
 one year ago
Best ResponseYou've already chosen the best response.1im trying to remember, please clear the concept for me

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1Intertial force , Maybe up my grade level. Just ignore it.

dan815
 one year ago
Best ResponseYou've already chosen the best response.1what does moment of interia give us exactly??

dan815
 one year ago
Best ResponseYou've already chosen the best response.1isnt it a torque about that point

dan815
 one year ago
Best ResponseYou've already chosen the best response.1maybe we can just completely ignored it?? there will be no rotation?

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1Bro, if there is inertial force. The problem 'd mention it.

dan815
 one year ago
Best ResponseYou've already chosen the best response.1oh okayy alright then lets work now lol

dan815
 one year ago
Best ResponseYou've already chosen the best response.1gotta write an expression for the horizontal distance from point C first as a function of the radius of the circle

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1No need , just get the torque around (A).

dan815
 one year ago
Best ResponseYou've already chosen the best response.1oh i know, umm since its root3 r, we can figure out this angle

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1Did you notice that AC is unknown too ?

dan815
 one year ago
Best ResponseYou've already chosen the best response.1true, ugh just feels like root3 r is giving enough restrictions

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1Listen to me , Torque around (A) !

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1Fb, mr will be omitted

dan815
 one year ago
Best ResponseYou've already chosen the best response.1i dont really see how there can be any torque about A , should the tourque be about B

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1R * r sqrt(3) = FG * r so FG = sqrt(3)R R = FG/sqrt(3)

dan815
 one year ago
Best ResponseYou've already chosen the best response.1nice, i still dont see how u did it

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.1Get torque around (A), sum of forces up = 0 , sum of forces down = 0 , You get 4 equations with 4 unknowns solve and you will get tan ( I am using paper for ease :D)
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