Torque Of Lever Arm in 1st/2nd Class Levers

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SUMMARY

The discussion focuses on calculating torque in first and second class levers, specifically addressing the impact of the lever's angle on torque calculations. In a first class lever, the torque is determined by the formula Torque = Force x Distance x sin(θ), where θ is the angle between the force and the lever arm. For a second class lever, the torque of a uniform mass lever arm is calculated by multiplying the weight of the lever by the distance from the fulcrum, with the example given being 1200 foot-pounds for a 200 lb lever arm at 6 feet from the fulcrum. The angle of the lever does affect torque calculations in both cases.

PREREQUISITES
  • Understanding of torque and its mathematical representation.
  • Familiarity with the principles of first and second class levers.
  • Knowledge of trigonometric functions, particularly sine.
  • Basic physics concepts related to force and distance.
NEXT STEPS
  • Study the application of Torque = Force x Distance x sin(θ) in various lever scenarios.
  • Explore the differences in torque calculations between first and second class levers.
  • Learn about the role of angles in mechanical advantage and torque in levers.
  • Investigate real-world applications of levers in engineering and physics.
USEFUL FOR

Students studying physics, engineers designing mechanical systems, and anyone interested in the practical applications of levers and torque calculations.

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Part 1 - Question About Torque Of Lever Arm in a 1st Class Lever

Homework Statement



A little while back I posted a question about incorporating the torque of a uniform mass and dimension lever arm into the principle of a 1st class lever.

Here is the thread for reference.
https://www.physicsforums.com/showthread.php?t=340234"

I gave an answer that was deemed correct, but I am curious if I am supposed to incorporate the angle the lever is at as well?

Does the angle the lever is at (e.g. left side down low under a rock, right side high up in the air waiting for force to be applied) effect the calculation of torque in a first class lever?

Homework Equations

Does the angle the lever is at (e.g. left side down low under a rock, right side high up in the air waiting for force to be applied) effect the calculation of torque in a first class lever?

The Attempt at a Solution



I'm not familiar enough with physics to understand how to incorporate angles/"sin" into these equations.

====================

Part 2 - Question About Torque Of Lever Arm in a 2nd Class Lever

Homework Statement



How is the torque of a lever arm (uniform mass, uniform dimension) calculated and incorporated into the "equation/math" of a 2nd class lever?

I have a 12 foot, 200 lb. second class lever arm of uniform mass and dimension.

My fulcrum is attached to the ground, and underneath the lever at 2 feet from the fulcrum is a car that I am trying to smash. Basically, I have a nutcracker type second class lever that uses a lever arm and the ground.

The Attempt at a Solution



Is the Torque of this Lever Arm (6 foot x 200 lb.) 1200 foot lbs. which is added to the effort force when trying to generate enough "down force" at 2 feet to adequately crush the car?

Does the starting angle of the lever matter in calculating torque in this case?-----------------I appreciate any feedback.
 
Last edited by a moderator:
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Q1) In the lever problem, if the fulcrum is not in the midpoint of the bar, find the distance between the midpoint and fulcrum and find the monent due to weight of the bar about the fulcrum.
Torque is always F*r*sinθ, θ is the angle between force and bar.
 

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