How could a lever be used to lift the object

In summary, this question is asking if there is a way to lift an object that is three times as heavy as you can lift without using a lever. The textbook says that the fulcrum could be placed at the end of the lever, which would result in a 3:1 ratio of lever arms. This could make a big difference in a practical situation depending on the applied force.
  • #1
AlexandraBoiko
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Hello everyone!

I'm new here and I have never been too good at physics, but now I've been trying to revise for the MCAT and I have stumbled across this question in "Kaplan MCAT Physics and Math Review":
If you have and object three times as heavy as you can lift, how could a lever be used to lift the object? Where would the fulcrum need to be placed?

I know the answer is obvious, and I have drawn the picture that I have attached to this post (where you place the fulcrum one quater of the way across the lever), but the textbook says that, alternatively, the fulcrum could be placed at the end with the object one-third of the way across the lever. It says that this would again result in a 3:1 ration of lever arms, meaning that only one-third of the original force is necessary, but I don't understand - how can there be a 3:1 when the object is placed one-third of the way across the lever?
Could anybody please draw the alternative position of the fulcrum described in the textbook? I just can't picture it:(
 
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  • #2
Sorry! I've just realized it's the wrong thread...
 
  • #3
AlexandraBoiko said:
...the fulcrum could be placed at the end with the object one-third of the way across the lever... I just can't picture it:(
See class 2 here:
https://en.wikipedia.org/wiki/Lever#Classes_of_levers
 
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  • #4
Thank you very much!
 
  • #5
Note the different directions of the forces for the three 'classes'. The choice could make a big difference to the choice in a practical situation. When the applied force would be downwards, it could be your weight and not your strength that would limit the maximum load. A weak, heavy person could find Class 1 very useful but an immensely strong lightweight would just manage to push himself up off the ground.
 
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  • #6
I see, thank you!:smile:
 

Related to How could a lever be used to lift the object

1. How does a lever work?

A lever is a simple machine that consists of a rigid bar or beam that is able to rotate around a fixed point, known as the fulcrum. When force is applied to one end of the lever, the other end is able to exert a greater force to move an object.

2. What is the principle behind using a lever to lift an object?

The principle behind using a lever to lift an object is based on the law of the lever, which states that the effort force applied to one end of the lever is equal to the load force on the other end multiplied by the distance from the fulcrum to the load.

3. How do you determine the ideal position of the fulcrum for lifting an object with a lever?

The ideal position of the fulcrum for lifting an object with a lever is determined by the relationship between the effort force and the load force. The closer the fulcrum is to the load, the greater the mechanical advantage and the less effort force is required to lift the load.

4. Can a lever be used to lift any object regardless of its weight?

Yes, a lever can be used to lift any object regardless of its weight as long as the effort force is greater than the load force. However, the length and position of the lever may need to be adjusted in order to achieve the desired mechanical advantage.

5. What are some real-life examples of how a lever is used to lift objects?

Some real-life examples of how a lever is used to lift objects include using a crowbar to remove a nail, using a wheelbarrow to move heavy objects, and using a seesaw at the playground. Levers are also used in many machines such as scissors, bottle openers, and car jacks.

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