Mechanical Advantage vs. Lever vs. Human Error

In summary, the conversation discusses the conflicting information regarding Mechanical Advantage and the Law of 1st Class Levers in designing a clamp mechanism. It is determined that for 1,000 lbs to lift 40,000 lbs, a lever ratio of either 40:1 or 1.243:1 is required. It is also clarified that the use of gravitational constant is not necessary in this scenario.
  • #1
BMR
1
1
This is my first post here, so pardon if forum guidelines/criteria require this to be designated elsewhere.

I am designing a clamp mechanism utilizing lever mechanics, and I am getting conflicting info regarding Mechanical Advantage and the Law of 1st Class Levers. Regarding MA, knowing that
300px-Lever_mechanical_advantage.png

e4516522ccaaa831010fc757760110894929d202


If:
FB = 40,000 lbs
FA = 1,000 lbs
Then: b = 40, a = 1, and the MA is 40:1

In regards to Levers (Specifically 1st Class Levers)
torque_lever.png

F2 = F1 L1 / L2

If:
FB = 40,000 lbs
FA = 1,000 lbs

Then:
40,000 = 1,000 (32.174 ft/s2 [gravity constant]) (L1 / L2)
40 = 32.174 (L1 / L2)
L1 / L2 = approx. 1.243 or 1.243:1.

So for 1,000 lbs to lift 40,000 lbs., either a 40:1 or 1.243:1 lever ratio is required. Am I simply wrong for factoring in a gravitational constant?
 

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  • #2
BMR said:
Am I simply wrong for factoring in a gravitational constant?
Yes. You get the same mechanical advantage whether the lever is on the Earth, the Moon or in free space.

On Edit: Assuming that F1 and F2 are either both pushing forces or both weights, that is.
 
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  • #3
BMR said:
So for 1,000 lbs to lift 40,000 lbs., either a 40:1 or 1.243:1 lever ratio is required.

@kuruman gave you the correct answer. But to amplify, if you move the whole apparatus to a planet with one half Earth's gravity, then the same weights would weigh 500 lbs and 20000 lbs, but the ratio 40:1 remains unchanged and the MA remains unchanged. That is why you don't need G.
 
  • #4
Another way to say the same thing as @anorlunda: If the number 1000 is a mass, then you multiply by g to get a weight which is a force. Here you have 1000 lbs which is already a force (the mass has already been multiplied by g) so it would be wrong to multiply by g again.
 
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Related to Mechanical Advantage vs. Lever vs. Human Error

1. What is the difference between mechanical advantage and a lever?

Mechanical advantage refers to the ratio of output force to input force in a machine or system. A lever is a simple machine that consists of a rigid bar or beam that pivots on a fulcrum and is used to amplify or redirect an applied force.

2. How does mechanical advantage affect the efficiency of a machine?

The higher the mechanical advantage, the more efficient a machine is at reducing the amount of force needed to do a certain amount of work. This is because the output force is greater than the input force, resulting in less effort required to achieve the same work.

3. How does the length of a lever affect its mechanical advantage?

The longer the lever arm, the greater the mechanical advantage. This is because the distance from the fulcrum to the point where the input force is applied increases, resulting in a smaller input force needed to produce a larger output force.

4. Can human error affect the mechanical advantage of a machine?

Yes, human error can affect the mechanical advantage of a machine. If the machine is not used correctly or is not maintained properly, the output force may not be as expected, resulting in a lower mechanical advantage. Additionally, incorrect measurements or calculations can also lead to human error and affect the mechanical advantage.

5. How can we minimize human error when using machines?

To minimize human error when using machines, it is important to thoroughly understand how the machine works and to follow the manufacturer's instructions carefully. Regular maintenance and proper training can also help reduce the risk of human error. Additionally, double-checking measurements and calculations can help catch any errors before they affect the mechanical advantage.

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