Find the magnitude of the torque

  • Thread starter jonnejon
  • Start date
  • #1
27
0

Homework Statement


Find the magnitude of the torque about P if a 68 lb force is applied as shown. Give your answer correct to the nearest integer.
12-4-40.gif



Homework Equations


t=r X F


The Attempt at a Solution


t = (4)(68)(sin30)
= 136
 

Answers and Replies

  • #2
LowlyPion
Homework Helper
3,097
5


Don't you want to consider the distance at which it is acting is 4*√2 ?

At the point of interaction then the ⊥ component of F looks to me like F*Cos15°
 
  • #3
2,411
711


Homework Statement


Find the magnitude of the torque about P if a 68 lb force is applied as shown. Give your answer correct to the nearest integer.
12-4-40.gif



Homework Equations


t=r X F


The Attempt at a Solution


t = (4)(68)(sin30)
= 136


You wrote what must have been intended to be a vector equation for the torque, t = r x F, because the cross product only makes sense if t, r, and F are all expressed as vectors. But then you proceeded to do a scalar calculation. Why not make your torque calculation in vector form using the determinant expression for the cross product and giving the resulting torque as a vector? Then if you need the magnitude of that vector, dot it with itself and take the square root of the result.
 

Related Threads on Find the magnitude of the torque

  • Last Post
Replies
2
Views
10K
Replies
4
Views
5K
Replies
2
Views
2K
Replies
4
Views
9K
Replies
1
Views
6K
  • Last Post
Replies
2
Views
6K
  • Last Post
Replies
8
Views
2K
  • Last Post
Replies
1
Views
16K
  • Last Post
Replies
1
Views
2K
Top