Shoulder abduction = 15¡ã
Abduction acceleration = 50/rad/s/s
Abduction velocity = 20 rad/s
Radius of gyration and COM location from joint = 25cm
Mass of hand + Arm = 8 kg
Force of middle deltoid =400N
Middle deltoid only active muscle
Force of theraband = 70N
Middle deltoid insertion = 15¡ã
¦µ=90
The question is: solve for joint reaction force compression on the bone.
Also draw an appropriate free body diagram for this problem
To solve for the joint reaction force compression on the bone, we need to consider the forces acting on the system.
First, let's draw a free body diagram for this problem. We will consider the forces acting on the system, including external forces and internal forces. The external forces include the force of the middle deltoid (400N) and the force of the theraband (70N), while the internal forces include the joint reaction force compression on the bone.
```
<----- Fdeltoid (400N)
. -------------
/ ^
/ |
/ |
/ |
/ |
/ |
/ <----------- Fjoint_reaction_compression
O / |
/
/
/
/
/
/
```
Now, let's analyze the forces acting on the system to solve for the joint reaction force compression.
1. Force of the middle deltoid (400N): This force is acting on the arm and causing abduction of the shoulder joint.
2. Force of the theraband (70N): This force is also acting on the arm and contributing to the abduction of the shoulder joint.
3. Joint reaction force (Fjoint_reaction_compression): This force is the reaction force at the point where the arm bone (humerus) meets the shoulder socket (glenoid). It acts in the opposite direction to the combined external forces to keep the system in equilibrium.
To solve for the joint reaction force compression, we need to sum up the forces acting on the system in the vertical direction, as we are interested in the compression force.
Summing up the forces in the vertical direction:
Fjoint_reaction_compression - Fdeltoid - Ftheraband = 0
Given that Fdeltoid = 400N and Ftheraband = 70N:
Fjoint_reaction_compression - 400N - 70N = 0
Fjoint_reaction_compression = 470N
Therefore, the joint reaction force compression on the bone is 470N.