Mechanics, degree of freedom question

[yugeci]

Homework Statement

Calculate the DoF (mobility) of the following system:

Homework Equations

[/B]
M = 3(L-1) - 2J₁ - J₂

(where L = number of links, J₁ is the number of full binary joints and J₂ is the number of half joints.

The Attempt at a Solution

I am very confident about there being 9 links, and 1 half-joint (the pin in the slot above the L link) but I am unsure about the number of full joints which I numbered here.

I know from 1-7 should be correct, but I don't know about the joints on the slider. Should there only be two binary joints for each like I put there? Which is basically one ternary joint... 2 on the rigid link 'L' and on the link to which the slider is attached.

And if I am correct I take it there is only 1 DoF then, which is the rotational of the circle attached to the top?

Help would be appreciated here.

 

[andrewkirk]

I presume the straight lines are strings. What happens when two straight lines meet at a little circle? Is it a pulley? Is it a post to which they are knotted? What about when three strings meet at a little circle? Can the little circles move?