Center of Gravity for nonuniform plank

[bullsangelsra]

Homework Statement

A box of negligible mass rests at the left end of a 1.90m, 23.5kg plank The width of the box is 75.0 , and sand is to be distributed uniformly throughout it. The center of gravity of the nonuniform plank is 50.0 from the right end.


I am lost pls help me

i know the torque is going to be zero, but i don't know where to go from here

 

[bullsangelsra]

is Xcm equal to the fulcrum or the center of gravity?

 

[bullsangelsra]

do i use the fact that torque equals zero or do i use the equation for the center of gravity..can someone just point me in the right direction?

 

[Doc Al]

Homework Statement

A box of negligible mass rests at the left end of a 1.90m, 23.5kg plank The width of the box is 75.0 , and sand is to be distributed uniformly throughout it. The center of gravity of the nonuniform plank is 50.0 from the right end.

What is the question? Please state the complete problem exactly as it was given.