Torque Problem

  • #1

Homework Statement



Find net torque.
2dbqwl0.jpg


Homework Equations




T = F(d) and T = F(d)sinx

Torque = T
Force = F
d = distance


The Attempt at a Solution



100(0) - 200(4)sin40 - 120(14) + 150(8) = -994.2 Nm

Did I do this correctly? Notice I crossed out the 400N also because I think that it does not affect it.
 

Answers and Replies

  • #2
LowlyPion
Homework Helper
3,097
5
Welcome to PF.

I think your second term is 6m from the pivot not 4m.

Your bottom force - 150N - is 15m from the pivot not 8m as your equation suggests.
 
  • #3
Ah, thanks, but how is 150N 15m away from the pivot point? Do I just go up? Sorry I do not understand :(
 
  • #4
LowlyPion
Homework Helper
3,097
5
Ah, thanks, but how is 150N 15m away from the pivot point? Do I just go up? Sorry I do not understand :(

It's the projection of the force to a line that is perpendicular to the pivot. That is the way you should be taking Torque.

For instance the one at an angle of 40° if you extended that out you would see that the lever arm that is perpendicular to the force is Sin40° times the 6m length.

For the bottom force it is acting horizontally, but it is acting through the vertical line from the pivot at a distance of 14 + 1 = 15.
 
  • #5
Ahhh...that clears up so many things. Thank you so much!
 

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