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 EnquiringMind Oct18-09 08:33 PM

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

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

1. The problem statement, all variables and given/known data

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.
http://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?

2. Relevant 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?

3. 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

1. The problem statement, all variables and given/known data

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.

3. 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.

 rl.bhat Oct18-09 10:46 PM

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

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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