Torque is same all along lever?

In summary, the conversation discusses the concept of torque and its relationship to force in keeping an arm and ball in a steady position. The individual initially thought torque and force were the same, but through the conversation, they realize that torque is the perpendicular force times the distance to the pivot point and is different from force. The conversation also explains that in order to hold the weight steady, the two torques must be equal, and the shorter lever arm requires a larger force. The individual eventually understands that torque represents the balance between the upward force of the forearm and the downward force of the ball.
  • #1
yosimba2000
206
9
Here's my background so you know where I'm having trouble. I've attached a picture.

I have to find the force produced by the muscle to keep the arm and ball at its current position in the picture. Now, I originally assumed Torque was Force in rotation, and intuitively thought you would need to use more force if you're closer to the pivot (shorter lever arm) than compared to the end (longer lever arm). I was right about force needed being greater as the lever arm got shorter, but I'm having touble understanding why the Torque along the lever must be the same. So, now I know Torque and Force are not the same.
Mathematically, I know there's only one right answer, but how about conceptually? What is torque if it's not force? What does it represent? Why isn't the torque increasing as the lever arm length decreases?

Thanks!
 

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  • #2
Torque is the perpendicular force times the distance to the pivot point. It is completely different from force. it is F*d.
Given that, you can see that as d decreases, so does the torque.

In this case, in order to hold the weight steady, the two torques must be equal. Because d for the muscle is much less than the other, it requires a much larger force.

does that help?
 
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  • #3
sorry, it still hasn't clicked. I mean, mathematically I agree with what you've said, but I still can't understand what Torque represents. What is it that makes it the same everywhere along the lever?
 
  • #4
it is not the same everywhere along the lever. torque is only defined about a pivot point. For the arm to hold the weight steady, the two torques about that point must be equal.

I am at a loss for offering an easy conceptual understanding. I just think of it as F*d.
 
  • #5
wait I think I've got it now. I was originally thinking of the upward force that the forearm would provide to support the ball, but now I'm thinking of the ball dragging down the forearm. And to balance that we need an upward force and the torques have to equal. Thanks a bunch!
 
  • #6
you're welcome :)
 

1. What is torque?

Torque is a measure of the rotational force applied to an object. In other words, it is the force that causes an object to rotate around an axis or pivot point.

2. How is torque calculated?

Torque is calculated by multiplying the force applied to an object by the distance from the pivot point to the point where the force is applied. The formula for torque is T = F x d, where T is torque, F is force, and d is distance.

3. What is a lever?

A lever is a simple machine that consists of a rigid bar or beam that rotates around a fixed point called a fulcrum. Levers are used to amplify or redirect force, making it easier to move or lift objects.

4. Is torque the same all along a lever?

Yes, torque is the same all along a lever. This is because the force and the distance from the fulcrum are directly proportional, meaning that as one increases, the other must decrease to maintain the same torque. In other words, the longer the lever, the less force is needed to produce the same amount of torque.

5. How does torque relate to mechanical advantage?

Torque and mechanical advantage are closely related. Mechanical advantage is a measure of how much a machine amplifies or redirects force. In levers, the longer the distance from the fulcrum to the point where the force is applied, the greater the mechanical advantage and the easier it is to move or lift an object. This is because a longer lever requires less force to produce the same amount of torque.

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