How could a lever be used to lift the object

Click For Summary

Discussion Overview

The discussion revolves around the mechanics of using a lever to lift an object that is three times heavier than the user can lift. Participants explore the placement of the fulcrum and the implications of different lever configurations as described in a textbook.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant describes a scenario where the fulcrum is placed one-quarter of the way across the lever, suggesting this allows the user to lift the heavier object.
  • Another participant references the textbook's alternative position of placing the fulcrum at the end of the lever with the object positioned one-third of the way across, questioning how this results in a 3:1 ratio of lever arms.
  • A later reply includes a link to a Wikipedia page discussing the classes of levers, indicating a desire for further clarification on the mechanics involved.
  • One participant notes the importance of the direction of forces in different classes of levers, suggesting that practical applications may vary based on the user's strength and weight.

Areas of Agreement / Disagreement

Participants express confusion regarding the textbook's explanation and the implications of different fulcrum placements. There is no consensus on the best approach or understanding of the lever mechanics presented.

Contextual Notes

Participants have not resolved the confusion regarding the 3:1 ratio and the placement of the fulcrum, indicating a need for further exploration of the concepts involved.

AlexandraBoiko
Messages
4
Reaction score
0
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:(
 
Physics news on Phys.org
Sorry! I've just realized it's the wrong thread...
 
  • Like
Likes   Reactions: AlexandraBoiko
Thank you very much!
 
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.
 
  • Like
Likes   Reactions: AlexandraBoiko
I see, thank you!:smile:
 

Similar threads

  • · Replies 18 ·
Replies
18
Views
3K
  • · Replies 12 ·
Replies
12
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 22 ·
Replies
22
Views
2K
Replies
7
Views
3K
  • · Replies 17 ·
Replies
17
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K