Question

. 0.30m
....|______|_________________________
....|...../\
...|_| <-- box with unknown mass

In the figure, the meterstick's mass is 0.200 kg and the string tension is 2.50 N . The system is in equilibrium.
Find the (a) unknown mass m and (b) the upward force the fulcrum exerts on the stick.

Answer 1

. ....0.30m
....|______|_________________________
....|........../\
...|_| <-- box with unknown mass

Answer 2

I can't figure out what they mean by a string in your drawing. If it's just the box and the ruler:
Sum of torques = zero

m*9.8*.3 = .2*9.8*.2

Answer 3

its a yardstick on a fulcrum. on the left hand side a block is hanging from a string. I tried to submit it with a url but it would not let me so i attempted to draw it out. the length of the meterstick from the lefthand side to the fulcrum is .30m