The discussion revolves around the mechanics of levers, specifically focusing on a lever that is 2 meters long used to lift a load of 1000 Newtons, with a mechanical advantage of 4. Participants explore the classification of the lever and the relationships between forces and distances involved in its operation.
Several participants have provided insights into the mechanics of levers, including the calculation of forces and moments. There is an ongoing exploration of the lever's configuration, with some participants questioning assumptions and definitions related to mechanical advantage and lever arms.
There are mentions of potential confusion regarding the length of the lever and the implications of the mechanical advantage, as well as the need for clarity on the position of the fulcrum. Some participants also reference static equilibrium conditions and the balance of forces in their reasoning.
Chi Meson said:As for which class lever... it could be anyone of the three. Just get the ratio of lever arms correct for whichever you pick.
--------------------------------------------------------------------------Fermat said:You're talking about a straight bar. With a load of 1000N at one end. And a force of P Newtons, say, at the other end which you have to work out, The lever/bar will have a fulcrum, or pivot point, at some point along it to give the MA of 4. You should also mark on the reaction at the fulcrum.
I knew that. Don't you think I knew that? I knew that. Of course I knew that. I did.HallsofIvy said:Not quite true. With a class 3 lever, the mechanical advantage is always less than 1.
-----------------------------------------------------HallsofIvy said:Since this has been here for a while now, with a class 1 lever (you have the fulcrum between the applied force and the load), the mechanical advantage is the length of the "application arm" (the distance between the application point and the fulcrum) and the length of the "load arm" (the distance between the load and the fulcrum). Here that must be 4. Draw a picture. label the length between the application and the fulcrum "4" and the length between the fulcrum and the load "1". What is the length of the entire lever?
Then why does the problem state "A lever 2 meters long..."scientist said:The length of the entire lever is 4m.
scientist said:The length of the entire lever is 4m.
The ma=4 x 1
-------------------------------------------------------------Fermat said:You're talking about a straight bar. With a load of 1000N at one end. And a force of P Newtons, say, at the other end which you have to work out, The lever/bar will have a fulcrum, or pivot point, at some point along it to give the MA of 4. You should also mark on the reaction at the fulcrum.
------------------------------------------------------------Fermat said:All the forces - load, effort and reaction (at the fulcrum) are considered to be in the same direction. Assuming they are all vertical, do a balance of Vertical Forces.
You haven't actually said that the force at the fulcrum = 1250N but, if so, then that is correct. Your downward forces (load plus effort) = 1250N, so your single upward force (fulcrum reaction) is also 1250N.scientist said:------------------------------------------------------------
Ok then,
the load = 1000 Newtons + force of 250 Newtons = 1250 Newtons, reaction force at the fulcrum.
Code:the effort = load ------ MA = 1000N ----- 4 = 250 Newtons
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Taking moments about the fulcrum:
Would clockwise moments = anticlockwise moments apply in this question?
This is what my book says.
Please post your reply and correct my answer.
scientist
They could, yes.scientist said:------------------------------------------------------------
...
Taking moments about the fulcrum:
Would clockwise moments = anticlockwise moments apply in this question?
...
----------------------------------------------------------------Fermat said:This is what you mean to post, yes?
You haven't actually said that the force at the fulcrum = 1250N but, if so, then that is correct. Your downward forces (load plus effort) = 1250N, so your single upward force (fulcrum reaction) is also 1250N.
Since the lever is assumed to be in static equilibrium, then
Σ Fv = 0
Σ Fh = 0
Σ T = 0
where Σ Fv is the sum of Vertical forces, Σ Fh is the sum of Horizontal forces, and Σ T is the sum of the Torques.
There are no horizontal forces and you have dealt with the vertical forces when finding the reaction at the fulcrum.
They could, yes.
Now you can do Σ T = 0, as one way of evaluating the position of the fulcrum
Take moments about the fulcrum. Call the distance from the fulcrum to the load as x. So what is the distance fornt the fulcrum to the effort?
Then the moment of the Load about the fulcrum is equal to the moment of the Effort about the fulcrum. Solve for x.
Careful. The ratio of the lengths is 4 to 1; this does not mean that the lengths are 4 meters and 1 meter! (Since the total length is only 2 meters, you know that can't make sense.)scientist said:The length between the application and the fulcrum is 4 meters. The length between the fulcrum and the load is 1 meter.
This is taken from the MA =4:1.
If you call the load-fulcrum distance X, then the two distances are X and 4X. Their sum must equal 2 meters, so X + 4X = 5X = 2 meters. Thus X = 2/5 meters.I added the 4 + 1 = 5 meters
The total lever length is 2 meters as stated in the question.
I divided the lever length of 2 meters by 5 meters.
2/5=0.4 meters.
-------------------------------------------Neohaven said:i'd say, by logics, that the fulcrum is at 1/5th of the length, starting at the end which lifts, am i right?