help with moments mechanics question

[maryam.aniss]

Hi,
so i've been really struggling with this moments question. i pasted the link below for the paper. its number 2 (b).

http://www.xtremepapers.com/Edexcel/index.php?dir=Advanced Level/Mathematics/2007 Jan/&file=M1Jan07Q.pdf

This is the answer paper :

http://www.xtremepapers.com/Edexcel...Level/Mathematics/2007 Jan/&file=M1Jan07A.pdf
Now what I don't understand is why they take the reaction at C equal to zero.

Thank you guys so much [in advance ]

 

[iblue]

i asked my teacher and he said that:
when the rock is at B the rod is on the point of turning about D which means that although the system is still in equilibrium the rod is barely touching C so theres almost no reaction.
hope this helps

 

[maryam.aniss]

i asked my teacher and he said that:
when the rock is at B the rod is on the point of turning about D which means that although the system is still in equilibrium the rod is barely touching C so theres almost no reaction.
hope this helps

yeah it did ! thanks alot

 

[iblue]

ur welcome