P: 1 ok, I know that being further away and using a fulcrum/pivot point from an object being moved takes less energy. i.e using a 4 foot crow bar to pry open something. But i can't grasp the concept of why being further away makes it so much easier. thanks
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P: 25,474
 Quote by mechadv44 ok, I know that being further away and using a fulcrum/pivot point from an object being moved takes less energy. i.e using a 4 foot crow bar to pry open something. But i can't grasp the concept of why being further away makes it so much easier. thanks
no, the energy is the same…

you can't get extra energy for nothing

only the force is less
 P: 4 same person who started thread, different name, sorry password problem.. I meant force though, can it be explained in plain english as opposed to just a formula why being further uses less force?thanks
P: 399

 Quote by mechadv44 ok, I know that being further away and using a fulcrum/pivot point from an object being moved takes less energy. i.e using a 4 foot crow bar to pry open something. But i can't grasp the concept of why being further away makes it so much easier. thanks
Clue.

The crow bar end you are pushing on, goes further than the other end.

Wayne
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goodness! are there 44 of you?
 I meant force though, can it be explained in plain english as opposed to just a formula why being further uses less force?thanks
force times distance equals work done (= energy supplied) …

if the two ends of the lever are at different distances from the fulcrum, so that they move different distances when the lever turns, then different amounts of force will do the same work, and will supply the same energy
 P: 4 I said that i already know that having a longer lever on the force side of the folcrum requires less force. what i'm asking is WHY WHY WHY does it make it easier? why is a longer lever so special if still moving the same object!?Is this just something that exists and can't be explained?
 P: 760 I think I asked this question once, too. The answer I got was essentially that yes, that's just the way the universe works. Fortunately it's a very simple thing and you'll see manifestations of it everywhere in everyday life. It quickly starts to just "make sense". Climbing stairs for example is easier than going straight up a wall. A door is easier to open if the handle is on the far side of the hinge. A piece of wood is easier to split when hit with the narrow end of an axe, a screw is easy to screw in and yet it holds things together very tightly, gears, levers, pulleys, even a winding road up a mountain....all take advantage of the fact that work is force x distance, and all these mechanisms simply trade distance for more force. Unfortunately there are also alot of concepts in physics where the answer is also "that's just the way it is", but they DON'T make any sense. You have to go in pretty deep to start getting to these concepts, though.
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 Quote by mechadv43 I said that i already know that having a longer lever on the force side of the folcrum requires less force. what i'm asking is WHY WHY WHY does it make it easier? why is a longer lever so special if still moving the same object!?Is this just something that exists and can't be explained?
Because conservation of energy requires it isn't a good enough answer?
P: 132
 Quote by mechadv43 I said that i already know that having a longer lever on the force side of the folcrum requires less force. what i'm asking is WHY WHY WHY does it make it easier? why is a longer lever so special if still moving the same object!?Is this just something that exists and can't be explained?
"WHY" questions are very hard to answer. Feynman explains just how hard it is. When asked why magnets attract each other, he explains that he can't give a simple answer. If you prefer reading a text instead of watching a video, here's a transcript.

For your particular "why" question, maybe Archimedes can help.
P: 694
 Quote by mechadv43 I said that i already know that having a longer lever on the force side of the fulcrum requires less force. what I'm asking is WHY WHY WHY does it make it easier? why is a longer lever so special if still moving the same object!?Is this just something that exists and can't be explained?
The most important concept is (as already typed by russ_watters in previous post) law of conservation of energy.

This law states that total energy in the system remains constant , i.e. energy can neither be created nor be destroyed.

Effort E Newtons upward
|
<-------------------------------------|-------------------------------------------------------->
|
Fulcrum
(Axis of rotation)
(L Newtons downwards)

Now I am not taking in account load arm and effort arm because lever is not in equilibrium.
Here L >>>> E , so by conservation of energy :
Work Input = Work output
L*d = E*x
(* is multiplication )
L/E = x/d
since L>>>>E , so x>>>>d

x arc >>>>>> d arc covered in circular path with Fulcrum as axis of rotation here.

So here
L* d arc = E*x arc

As work = force * displacement

By conservation of energy we get this result.

Note : We talk about like
Load * Load arm = Effort * Effort arm , when lever is in equilibrium. Longer the effort arm , more the mechanical advantage. This is principle of lever.
Obviously think logically that one guy sitting at longer distance apply force less to counterbalance because distance being more will dominate the counter force effect !Its centre of gravity will be displaced and will be posed with less friction....
(And please we neglect friction ! ) Yes ! Centre of gravity will dominate at the side of the guy sitting at longer distance.
 PF Patron Sci Advisor Thanks Emeritus P: 38,395 Let's say you have a lever of length 6 m and the pivot is 2 m from the object being moved so that your end of the lever is 4 m from the pivot. As you move the lever through angle $\theta$ radians, you will have moved your end of the lever a distance $4\theta$ meters. At the same time the object will have moved a distance of $2\theta$ meters. Since work (energy) is "force times distance" and energy is conserved, the work you do, the force you apply to the lever times $4\theta$ must be equal to the force applied to the object by the lever times $2\theta$: $$F_{object}(2\theta)= F_{you}(4\theta)$$ which reduces to $$F_{object}= 2F_{you}$$ Showing a mechanical advantage of 2 to 1- the force applied to the object is twice the force you apply to the lever.
 P: 5,462 I'm suprised no one has mentioned the link from mechanical advantage to velocity ratio and mechanical efficiency.
 PF Patron Sci Advisor P: 1,767 Here's a way to understand mechanical advantage in general terms. Energy is always conserved. [edit: as mentioned by Tiny-Tim] When using any kind of pulleys or gears or levers, the power transferred through (work per unit time) is constant and so the work done over an interval is constant. So, for example if you have a lever, applying a force F on one side and moving a distance $\Delta x$, it yields an amount of work $\Delta W = F\Delta x$ That must be equal to the work done on the other side of the lever so you get: $F_1 \Delta x_1 = F_2 \Delta x_2$ You can thus use mechanical advantage to double the force but it will halve the motion. (classic lever with fulcrum 2/3 at 2/3 the length so the two sides has a 2/3 : 1/3 or 2:1 ratio. Apply 10 Newtons to one side and you'll get 20 Newtons on the other... however move the one side 5 cm and the other side will only move 2.5 cm. 10*5 = 20 * 2.5 = 50 newton cm = .5 newton m = 0.5 joules. You can also generalize to pressures and change of volume torques and angles of rotation and also to voltage and flow of charge. Work = force times $\Delta$distance = pressure times $\Delta$volume = torque times $\Delta$radian angle = voltage $\Delta$charge likewise time rate of change of work which is power is: power = force times speed= pressure times volumetric flow rate = torque times angular speed = voltage times current. This assumes the ideal case with 100% transmission efficiency. Friction and other loss effects will suck up some of the energy or power in an actual example. So assume you want to lift an engine block which masses 1/2 a metric ton=500kg. It thus weighs 500kg x 9.8m/s^2 = 500 x 9.8=4900 newtons. (Multiply mass times gravitational acceleration to get weight as a force) You wish to lift it 2 meters. That means you want to do 9800 Joules of work. (Joule = Newton Meter) You can do this with a 5:1 pulley system where you pull on the rope with a 100kg lifting force (980 newtons=1/5 the force) by pulling with that force 5 times as far (10 meters). You can also do this with a pneumatic lift applying say 1 torr = (100,000 Pa = 100,000N/m^2 = 100,000 Joules / meter^3) by displacing .098 cubic meters= 98000cc's. (or use 100 torr displacing 980cc's that's a bit under 1 atmosphere pressure) Or use a 240V electric wench which will require 9800/240 ~ 40.83Coulombs. (at 10Amps that will lift it in 4.083 seconds.) Mechanical advantage is a matter of spreading the work out over a greater amount of motion so it requires less force. In the end though work input = work output. Archimedes said “Give me a place to stand and with a lever I will move the whole world.” what he neglected to say was “but not very far ; ) ”
 P: 4 Sorry if the answer’s already posted and I’m just not bright enough to see it. But, what I’m really asking is can a person (the smartest person ever for argument’s sake) move a lever with mechanical advantage and actually understand/feel it in their mind how it‘s requiring less force, or is it ‘just how the universe works?’ Is it how sankalpmittal said, center of gravity will dominated at the longer side of the lever? thanks
P: 694
 Quote by mechadv43 Sorry if the answer’s already posted and I’m just not bright enough to see it. But, what I’m really asking is can a person (the smartest person ever for argument’s sake) move a lever with mechanical advantage and actually understand/feel it in their mind how it‘s requiring less force, or is it ‘just how the universe works?’ Is it how sankalpmittal said, center of gravity will dominated at the longer side of the lever? thanks
See the post of Michael C i.e. post 9 , it has link to a good site which has your answer I think.

I think you are confusing principle of lever with law of conservation of energy.

Now see , in above image that lever is balanced at fulcrum with distance d > distance D
Now since lever is balanced , then anticlockwise moments equals clockwise moments.

Then ,
w*d = W*D
since w<W and d>D
Then
W/w = d/D
Now see that resultant force will act on the point which divides the ratio of distance "d+D" in d:D.
As we know that d> D so the resultant force will dominate at the side of distance d.
Hint : Here centre of gravity will be at midpoint of distance "d+D" that is at the side left of fulcrum in this system ! Also think about section formula of coordinate geometry.
W/w = mechanical advantage as well
M.A. = d/D
Hence the mechanical advantage will be with the small stone of weight w.

Does this help ?

Edit : Tiny-Tim thought that you were asking about law of conservation of energy in which work input equals work output. That's different matter although here it applies as its a universal law. Halls Of Ivy too answered your question in different way. jambaugh too had a great explanation.
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