# Finding net torque problem

## Homework Statement

Find the net torque on the wheel in the figure below about the axle through O, taking a = 13.0 cm and b = 31.0 cm. (Assume that the positive direction is counterclockwise.)
pic: https://fbcdn-sphotos-c-a.akamaihd...._=1470130918_26fa32f17821823200ba75439cef0a52
[/B]

τ=f⋅d[/B]

## The Attempt at a Solution

just sum all for torque, I thought you could just go
τ1=9.0N ⋅ 0.31m = 2.79 n⋅m
τ2=10.0N⋅0.31 = 3.1 N⋅ m
but the torque component with the angle shown, I calculated it the same and then summed all the values of torque together, and it said it was wrong, so im assuming that you have to add something like a cosine or sine into that component because it isnt in a horizontal or vertical direction but 150° below the horizontal (positive x axis) any tips on how to solve this,????

## Answers and Replies

Orodruin
Staff Emeritus
Homework Helper
Gold Member
I calculated it the same
This does not actually show us what you did. Please specify the values you put in and the result you got.

This does not actually show us what you did. Please specify the values you put in and the result you got.
i dont understand how it doesnt show what i did? i completely explained what i did. the two net torques i gave how i calculated them and got 2.79 N.m and 3.1 N.m and said i did the same for the third component so obviously following that i went 12.0N x 0.13m which gave me 1.56 N.m, then i said i summed all my values for torque together, thus 2.79+3.1+1.56 which equals 7.45N.m but that value was incorrect. Does that explain it anymore or was there something else you need to know??

haruspex
Homework Helper
Gold Member
2020 Award
i completely explained what i did.
No, you left out this initially:
following that i went 12.0N x 0.13m

2.79+3.1+1.56
Think about directions (more precisely, "sense").

Orodruin
Staff Emeritus