Woman standing on ball of foot - torque

In summary, the problem is asking for the torque, or rotational force, produced by the normal force acting on the ball of a woman's foot. The distance from the normal force to the point P is given as D, and the force itself is N. To calculate the moment arm, we drop a perpendicular line from the force to the pivot point, which is already given as D. So the equation for torque becomes N *- D.
  • #1
superdave
150
3
Now consider a woman standing on the ball of her foot as shown. A normal force of magnitude N acts upward on the ball of her foot. The Achilles' tendon is attached to the back of the foot. The tendon pulls on the small bone in the rear of the foot with a force F. This small bone has a length x, and the angle between this bone and the Achilles' tendon is phi. The horizontal displacement between the ball of the foot and the point P is D.

11352_d.jpg


Find Torque_N about point P due to normal force.

Express in terms of N and any other quantities given.

So, help?
 
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  • #2
Seems pretty straightforward. How do you calculate torque?
 
  • #3
Distance to pivot point * moment arm * force?

I know the distance is sqrt(N^2+D^2), the force is N. But then the moment arm I'm having trouble with. It's sin of the angle, but we don't have the angle. But the sin should be (N/sqrt(N^2+D^2)) Opposite over Hypotenuse. But that's not it.
 
  • #4
It's the sine of the angle between the lever arm and the force, so N is the adjacent side, and D is the opposite side.
 
  • #5


OP, I was in the same mindset you were in when I first attempted this problem. It is actually not that complicated if you look past the common formulas. To get the moment arm you drop a perpendicular line from the force to the pivet point. The normal force is pointing straight up so dropping a 90 degree line is actually the "D" variable already given.

So knowing that Torque = Force * (moment arm) it is simply N *- D.
 

Related to Woman standing on ball of foot - torque

1. What is the purpose of a woman standing on the ball of her foot?

The purpose of standing on the ball of the foot is to shift the body's weight forward onto the toes, which can improve balance and stability. This can also help with certain movements and activities, such as dancing and sports, by allowing for quick changes in direction and faster movements.

2. Does standing on the ball of the foot create torque?

Yes, standing on the ball of the foot can create torque, which is a twisting force that causes rotation. This is because the weight of the body is shifted forward, causing a rotational force around the ankle joint.

3. How does standing on the ball of the foot affect the body's alignment?

Standing on the ball of the foot can change the body's alignment by shifting the weight forward and causing the hips to tilt forward. This can create a more upright posture and engage the muscles in the legs and core.

4. Is standing on the ball of the foot a common exercise or movement?

Yes, standing on the ball of the foot is a common exercise and movement in various forms of dance, gymnastics, and martial arts. It is also commonly used in physical therapy and rehabilitation to improve balance, coordination, and strength.

5. Are there any potential risks or injuries associated with standing on the ball of the foot?

Standing on the ball of the foot can put extra strain on the calf muscles, Achilles tendon, and ankle joint. This can lead to muscle strain, tendonitis, or ankle injuries if not done properly or with excessive force. It is important to warm up and stretch before attempting this movement and to start with lower levels of intensity and duration.

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