- #1
Jason Ko
- 21
- 6
- TL;DR
- I found this theorem in D. Morin's book on mechanics. How to prove it mathematically? Does it have a name?
I The direction of three forces acting on a line has to be concurrent?
Click For 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.
- #2
- 22,820
- 14,875
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.
- #3
Jason Ko
- 21
- 6
Thanks! I was being stupid
- #4
- 15,866
- 9,001
Probably you didn't read the "simple" proof provided below the statement that you highlighted in the textbook.Jason Ko said:
- #5
- 22,820
- 14,875
Nor I. Good thing I agree with Morin though …kuruman said:
Power = Force v Speed
Power of my horse = 104kgx9.81m/s^2 x 0.732m/s = 1HP =746W
Force/tension in rope stay the same if horse run at 0.73m/s or at 15m/s, so why then horse need to be more powerfull to pull at higher speed even if backward force at him(rope tension) stay the same?
I understand that if I increase weight, it is hrader for horse to pull at higher speed because now is backward force increased, but don't understand why is harder to pull at higher speed if weight(backward force)...
Similar threads
- · Replies 10 ·
- · Replies 13 ·
- · Replies 9 ·
- · Replies 3 ·
- · Replies 8 ·
- · Replies 7 ·
- · Replies 5 ·
- · Replies 75 ·