Static Equilibrium: Homework Questions

[Speedking96]

Homework Statement

I have a question about the following question:

Firstly, shouldn't there be a normal force for each hand (part a), but here they treat it as one normal force.

Also in part b, why isn't the torque for Fn1h = 0? Since that is the pivot point, isn't the moment arm zero?

 

[Simon Bridge]

Firstly, shouldn't there be a normal force for each hand (part a), but here they treat it as one normal force.

How is the result different if you give each hand a separate normal force?

Also in part b, why isn't the torque for Fn1h = 0? Since that is the pivot point, isn't the moment arm zero?

$F_{N1} \neq 0$ and $h\neq 0$ therefore $F_{N1}h \neq 0$ ... take a closer look: what are they using for the pivot point in that calculation?

 

[Speedking96]

Wow. The pivot point is the location of the foot and N1 is for the hands. I see. Thank you.

 

[Simon Bridge]

Well done. Remember all those horizontal mean static problems - beam between two supports?
Remember how you'd do a sum-of-torques for each support as the pivot?

 

[Speedking96]

I actually don't know what you're referring to as I am learning torque and rotational dynamics on my own (on my final exam tomorrow and my teacher rushed everything on rotation ) - I don't think I've come across a problem like that

 

[Simon Bridge]

Have a look at:
http://www.pstcc.edu/departments/natural_behavioral_sciences/Web%20Physics/Experiment%2002-1320.htm
... it counts as essential physics.

Have you done levers?