I The direction of three forces acting on a line has to be concurrent?

  • I
  • Thread starter Thread starter Jason Ko
  • Start date Start date
  • Tags Tags
    Direction Forces
AI Thread Summary
In a system in equilibrium, if the third line of action does not intersect the crossing point of two force lines, a net torque is created, which contradicts the conditions for equilibrium. The discussion highlights the importance of understanding the proof provided in the textbook regarding this concept. Participants acknowledge a lack of initial comprehension but express agreement with the established principles. The exchange emphasizes the necessity of careful reading and comprehension in physics discussions. Understanding these fundamental concepts is crucial for grasping equilibrium conditions.
Jason Ko
Messages
21
Reaction score
6
TL;DR Summary
I found this theorem in D. Morin's book on mechanics. How to prove it mathematically? Does it have a name?
1709042028580.jpeg
 
Physics news on Phys.org
Take the point of crossing of two of the force lines of action. If the third line of action does not pass through that crossing, there is a net torque and therefore this cannot happen for a system in equilibrium.
 
Thanks! I was being stupid
 
Jason Ko said:
Thanks! I was being stupid
Probably you didn't read the "simple" proof provided below the statement that you highlighted in the textbook.
 
kuruman said:
Probably you didn't read the "simple" proof provided below the statement that you highlighted in the textbook.
Nor I. Good thing I agree with Morin though … 😛
 

Thread 'The Effect of Linear and Rotational Motion on Measured Weight'

Consider an extremely long and perfectly calibrated scale. A car with a mass of 1000 kg is placed on it, and the scale registers this weight accurately. Now, suppose the car begins to move, reaching very high speeds. Neglecting air resistance and rolling friction, if the car attains, for example, a velocity of 500 km/h, will the scale still indicate a weight corresponding to 1000 kg, or will the measured value decrease as a result of the motion? In a second scenario, imagine a person with a...
View full post »

Thread 'Coulomb gauge implies instantaneous radial electric field?'

Scalar and vector potentials in Coulomb gauge Assume Coulomb gauge so that $$\nabla \cdot \mathbf{A}=0.\tag{1}$$ The scalar potential ##\phi## is described by Poisson's equation $$\nabla^2 \phi = -\frac{\rho}{\varepsilon_0}\tag{2}$$ which has the instantaneous general solution given by $$\phi(\mathbf{r},t)=\frac{1}{4\pi\varepsilon_0}\int \frac{\rho(\mathbf{r}',t)}{|\mathbf{r}-\mathbf{r}'|}d^3r'.\tag{3}$$ In Coulomb gauge the vector potential ##\mathbf{A}## is given by...
View full post »
Thread 'Griffith, Electrodynamics, 4th Edition, Example 4.8. (First part)'

Thread 'Griffith, Electrodynamics, 4th Edition, Example 4.8. (First part)'

I am reading the Griffith, Electrodynamics book, 4th edition, Example 4.8 and stuck at some statements. It's little bit confused. > Example 4.8. Suppose the entire region below the plane ##z=0## in Fig. 4.28 is filled with uniform linear dielectric material of susceptibility ##\chi_e##. Calculate the force on a point charge ##q## situated a distance ##d## above the origin. Solution : The surface bound charge on the ##xy## plane is of opposite sign to ##q##, so the force will be...
View full post »

Similar threads

B Understanding Newton's Third Law and the Net Force on Objects
Replies
10
Views
355
B Determine forces acting on double inclined plane
Replies
13
Views
2K
I Directional magnetic field
Replies
9
Views
1K
B Normal force in case of inclined plane and banked turn
Replies
3
Views
2K
I Distributed Forces and force density....
Replies
8
Views
3K
B Forces on a passenger in a car?
Replies
7
Views
3K
B What forces act on a bar when you do pull-ups?
Replies
5
Views
2K
I Is it accurate to say work is motion against an opposing force?
2
Replies
75
Views
4K
B Electric Field Direction: Are We Assuming a Universal Positive Frame?
Replies
20
Views
1K
B Would there be any varying forces acting on individual wells in rotation? (stir/shaker plate)
Replies
9
Views
1K

Hot Threads

Recent Insights

Back
Top