Solving Biomechanics Question: Hip and Knee Velocity Calculations

[fratjock20]

Biomechanics Question. Please Help!

Hey everyone, I need help with the following question:

Vertical velocity of the hip = 2.1 m/sec
Horizontal velocity of the hip = 1.7 m/sec
Angular velocity of thigh = 4.6 rad/sec
Thigh length = 0.36 m

a) Calculate the absolute horizontal velocity of the knee when the thigh is perpendicular to the ground.

Calculate the velocity of the knee with respect to the hip at any point (assume that the hip velocites are constants).

c) Calculate the absolute horzontal velocity of the knee when the thigh is at an angle of -36 degrees (with respect to the horizontal) and traveling in a counterclockwise direction.

Thanks in advance for your help!

 

[Danger]

This sounds very much like a homework question, in which case it is posted contrary to forum guidelines. There is a section devoted to homework. If this were a serious scientific enquiry, it would not have been worded as something from an assignment.

 

[kyle8921]

I would be happy to assist you with this biomechanics question. First, I would like to clarify that biomechanics is the study of the mechanical principles of movement and how they apply to living organisms. In this case, we are looking at the movement of the hip and knee joints.

a) To calculate the absolute horizontal velocity of the knee when the thigh is perpendicular to the ground, we can use the formula Vknee = Vhip + Vthigh, where Vhip is the horizontal velocity of the hip and Vthigh is the horizontal component of the thigh's angular velocity. Since the thigh is perpendicular to the ground, its horizontal component of angular velocity is zero. Therefore, the absolute horizontal velocity of the knee would be equal to the horizontal velocity of the hip, which is 1.7 m/sec.

b) To calculate the velocity of the knee with respect to the hip at any point, we can use the same formula as above. However, since the hip velocities are constant, we can simply use the angular velocity of the thigh to determine the knee's velocity at any point. This would be equal to 4.6 rad/sec * thigh length (0.36 m), which gives us a velocity of 1.656 m/sec.

c) To calculate the absolute horizontal velocity of the knee when the thigh is at an angle of -36 degrees and traveling in a counterclockwise direction, we can use the same formula as in part (a). However, we need to take into account the angle of the thigh in relation to the horizontal. This can be done by using the cosine function. The formula would be Vknee = Vhip + (Vthigh * cos(angle)), where the angle is -36 degrees. Plugging in the given values, we get Vknee = 1.7 + (4.6 * cos(-36)) = 3.02 m/sec.

I hope this helps you with your biomechanics question. It is important to remember that these calculations are based on idealized conditions and may differ in real-life scenarios due to factors such as muscle activation and joint stability. Keep in mind that biomechanics is a complex field and there may be other factors to consider in a more detailed analysis.