Discover the Natural Swinging Period of the Human Leg | Need Help Now!

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The discussion centers on calculating the natural swinging period of the human leg, modeled as a physical pendulum with two rods representing the upper and lower leg. The upper rod is 54 cm long and has a mass of 7.0 kg, while the lower rod also measures 54 cm and weighs 4.3 kg. Participants emphasize the need to show work to receive assistance, and one suggests using the center of mass and pendulum equations to find the period. There is confusion regarding the moment of inertia and which mass to use in calculations. The conversation highlights the importance of understanding physical principles to solve the problem effectively.
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The human leg can be compared to a physical pendulum, with a "natural" swinging period at which walking is easiest. Consider the leg as two rods joined rigidly together at the knee; the axis for the leg is the hip joint. The length of each rod is about the same, 54 cm. The upper rod has a mass of 7.0 kg and the lower rod has a mass of 4.3 kg.

Calculate the natural swinging period of the system.
Express your answer using two significant figures.

I really need help..i am totally lost and it;s due in 3 hours...
 
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sungjoooneee said:
The human leg can be compared to a physical pendulum, with a "natural" swinging period at which walking is easiest. Consider the leg as two rods joined rigidly together at the knee; the axis for the leg is the hip joint. The length of each rod is about the same, 54 cm. The upper rod has a mass of 7.0 kg and the lower rod has a mass of 4.3 kg.

Calculate the natural swinging period of the system.
Express your answer using two significant figures.

I really need help..i am totally lost and it;s due in 3 hours...

Show some effort first!

I haven't seen this two pendulum system before but you must show your work before anyone else would help you (see rules).

I can say assume it as one rod and find center of mass
using the pendulum equations (that mgl = something .. I don't have my book near me for reference and I cannot remember those standard equations correctly) find T. (but this is just a guess)
 
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The lower leg will move about the knee at the endpoints of the swings and for one of the 2 swings in particular. Since there is no air resistance, you may avoid working with that; what you might want to take into account towards are fluctuations in the moment of inertia and see if there is any effect on the overall rotation.
 
T = 2pi Squareroot (I//mgh)

how do you determine moment of inertia, and h..

For m do i use 7.0 kg or 4.3 kg
 
Thread 'Collision of a bullet on a rod-string system: query'

Thread 'Collision of a bullet on a rod-string system: query'

In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
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