The discussion clarifies the mechanics of lifting a bucket, identifying the elbow joint as the fulcrum in this action. When lifting, the biceps muscle exerts force at the insertion point on the radius bone, not at the shoulder. This scenario exemplifies a class 3 lever system, where the elbow acts as the pivot point, and the force is applied through the biceps tendon. Understanding these mechanics is crucial for grasping the physics of torque application in human movement.
PREREQUISITESThis discussion is beneficial for students of physics, biomechanics researchers, physical therapists, and fitness professionals looking to understand the mechanics of lifting and force application in the human body.
Normally when you pick up a bucket you apply a force to the bucket (through the CoM - Centre of Mass - of the bucket), but no torque about the CoM.David lopez said:if i pick up a bucket i apply torque to the bucket. my shoulder is the fulcrum. is my elbow the point of application of force? just trying to understand the physics?
If you lift a bucket, there are at least two levers in operation.David lopez said:if i pick up a bucket i apply torque to the bucket. my shoulder is the fulcrum. is my elbow the point of application of force? just trying to understand the physics?
so where would the application of force be?jbriggs444 said:If you lift a bucket, there are at least two levers in operation.
Let us suppose that you have grabbed the bucket by its bail handle. The bucket is currently on a table in front of you. Your upper arm is near vertical and your lower arm is extended in front of you to the bucket.
You lift the bucket. Your elbow joint is acting as a fulcrum. Your biceps muscle is contracting, putting a large force on the tendon that attaches it to the radius bone in your forearm. Your hand rises as a result and the bail handle provides the load against which your hand lifts.
Considering the lower arm only, that makes this a class 3 lever.
At the point where the biceps tendon attaches to the radius.David lopez said:so where would the application of force be?
No. Not at the shoulder. Not near the shoulder. At the point where the biceps meets the radius. The point labeled "Insertion of the Biceps Bracchi". We are considering the lower arm as the lever.David lopez said:so at the shoulder or near the shoulder?