URGENT!! PLEASE HELP ASAPPP!!
What are the directions and magnitudes of joint reaction forces (both horizontal and vertical) and moments of the KNEE (running)?
Data you will need are:
Mass of participant: 67.2 kg Running direction: anterior
Joint: Knee
Segment: Lower Leg
Knee coordinates (m) y: 4.207, z: 1.313
COM coordinates (m) y: 4.235, z: 1.141
knee acceleration (m/s^2) y: 1.762, z: -3.738
COM acceleration (m/s^2) y: 0.511, z: -5.293
COM: Angular velocity (rad/s) = -19.997. Angular acceleration (rad/s^2) = -0.806.
COM: Linear acceleration (m/s^2) y: 0.511, z: -5.293
1. MUST draw free body diagram of tibia segment.
2. List all steps in detail of how to conduct inverse dynamics.
To find the directions and magnitudes of joint reaction forces and moments of the knee during running, you can follow these steps using inverse dynamics:
Step 1: Draw a free body diagram of the tibia segment:
- Draw a diagram representing the tibia segment, indicating the forces acting on it.
- Label the weight of the segment acting downward from its center of mass.
- Include arrows representing the joint reaction forces and moments that you want to find.
Step 2: Conduct inverse dynamics:
1. Calculate the linear acceleration of the knee joint:
- The linear acceleration of the knee joint is the same as the linear acceleration of the center of mass (COM) of the lower leg segment, which is given as 0.511 m/s^2 in the y-direction and -5.293 m/s^2 in the z-direction.
2. Calculate the angular acceleration of the knee joint:
- The angular acceleration of the knee joint is the same as the angular acceleration of the COM of the lower leg segment, which is given as -0.806 rad/s^2.
3. Calculate the net joint torques:
- Use the equation: net joint torque = segment moment of inertia * joint angular acceleration.
- The segment moment of inertia can be determined using the mass and the coordinates of the center of mass (COM) and knee joint.
4. Decompose the net joint torque into horizontal and vertical components:
- Since the running direction is specified as anterior, the horizontal component (along the x-axis) represents the joint reaction force, and the vertical component (along the y-axis) represents the joint moment.
- Use trigonometry to calculate the magnitudes of the horizontal and vertical components.
5. Calculate the joint reaction forces and moments:
- The joint reaction forces and moments can be determined by subtracting the effects of gravitational forces from the net joint forces and moments calculated in the previous steps.
- The gravitational forces can be determined using the mass of the participant and the angle between the lower leg segment and the vertical axis.
By following these steps, you should be able to determine the directions and magnitudes of the joint reaction forces (both horizontal and vertical) and moments of the knee during running.