Question #d2b05

1 Answer
Mar 1, 2018

I get a non sensical result which suggests the system as shown cannot work

Explanation:

To start, we can calculate the normal reaction at the pivot which we will call N. Since it is in equilibrium:
N+30=20 + (0.5times10) + 40
N=35
Applying the principle of moments and taking moments about the far right end of the stitck, and defining the distance from this end to the pivot as x
Clockwise moments = anti-clockwise moments
35x+ (30times0.75) =(5times0.5) + (20times0.9)
35x=-2
x=-0.057m
This negative distance suggests the system doesn't work as shown. I have tried taking moments at different points and get the same answer. I am assuming the c.g is half way along (also note the mass is shown as 500g whereas the question says 200g). I am taking the stick as 1m long as implied by its name