Minimum Force to Lift a Cylinder: Explained

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SUMMARY

The discussion focuses on calculating the minimum force required to lift a cylinder over a step, emphasizing the relationship between torque and force. The key conclusion is that the minimum torque exerted by the lifting force must equal the torque due to the weight of the cylinder for the force to be minimized. The angle of application (alpha) is crucial, as it determines the efficiency of the force used to overcome the weight's torque. Understanding this relationship clarifies why equal torques indicate minimum force.

PREREQUISITES
  • Understanding of torque and its calculation
  • Basic principles of mechanics, specifically forces and moments
  • Knowledge of angular acceleration concepts
  • Familiarity with lifting techniques and angles of force application
NEXT STEPS
  • Study the principles of torque in physics, focusing on the formula τ = r × F
  • Learn about the relationship between force, angle, and torque in lifting scenarios
  • Explore practical applications of minimum force calculations in engineering
  • Investigate the effects of different angles on lifting efficiency and force requirements
USEFUL FOR

Students studying physics, mechanical engineers, and anyone interested in the mechanics of lifting and torque applications.

asi123
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Homework Statement



Hey, guys.
I have this guy trying to lift this cylinder pass the step with minimum force and so is the question, what's the minimum power that he needs to use and at what angle (alpha)?
I also added the solution.
The thing I don't understand is, why when the momentum of the weight and the momentum of the force equal one to another, you can say that the force is minimum? I mean, I can understand that there's no angular acceleration, but why is it minimum (the force)?
10x.

Homework Equations





The Attempt at a Solution

 

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asi123 said:
The thing I don't understand is, why when the momentum of the weight and the momentum of the force equal one to another, you can say that the force is minimum?
You mean (I presume) moment (or torque) not momentum. The torque due to the weight is what the man must overcome to lift the cylinder over the step. So the minimum torque that he must exert is equal to the torque due to the weight. Of course, he'd choose an appropriate angle to use the minimum force to produce that torque.
 
Doc Al said:
You mean (I presume) moment (or torque) not momentum. The torque due to the weight is what the man must overcome to lift the cylinder over the step. So the minimum torque that he must exert is equal to the torque due to the weight. Of course, he'd choose an appropriate angle to use the minimum force to produce that torque.

Thanks.
 

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