Force and momentum in gymnastics position

In summary: If you take moments about one shoulder joint, you will have a set of forces between that joint and the corresponding hand, each exerting a torque at his shoulder. This will be equal and opposite to the sum of torques from the forces between that shoulder and the other hand. They are asking for the magnitude that these two torques have (each). The torque that the man has to generate about is shoulder to stop his arms rotating is 297 N.
  • #1
alejandro7
13
0
Hi. I'm trying to solve this problem but I'm not sure my solution is right:

"Suppose that a male gymnast wishes to execute an iron cross during a gymnastics session. The total mass of the gymnast is 60 kg. Each ring supports half of the gymnast's weight. Assume that the weight of one of his arms is 5% of his total body weight. The distance from his shoulder joint to where his hands hold the rings is 50 cm. The distance from his hands to the center of mass of his arm is 34 cm. The horizontal distance from his shoulder to the center of mass of his body is 19 cm (from the shoulder to the middle of the chest, not the actual center of mass of the body). If the gymnast is at rest, how much force and torque are at one of his shoulder joints?"

My attempt:

∑Fy : -W+R-Warm+W/2 = 0
where W = (60 kg)(9.8 m/s2) = 588 N , R is the reaction force on the shoulder joint, Warm = (0.05)(60 kg) = 3 kg

Solving, R = 297 N

However, I don't know what the problem means by the torque "at" his shoulder joint. Is it the torque generated by R (i.e. (R)(0.19 m)) or the sum of about the shoulder (0)?

Thanks.
 
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  • #2
I would assume they mean the torque that the man has to generate about the shoulder. However I think I would begin my answer with.. The person is at rest so the net torque about any point sums to zero. The torque that the man has to generate about is shoulder to stop his arms rotating is...
 
  • #3
The torque that the man has to generate about is shoulder to stop his arms rotating is the reaction force (R) times the distance. But which distance?
 
  • #4
alejandro7 said:
The torque that the man has to generate about is shoulder to stop his arms rotating is the reaction force (R) times the distance. But which distance?
If you take moments about one shoulder joint, you will have a set of forces between that joint and the corresponding hand, each exerting a torque at his shoulder. This will be equal and opposite to the sum of torques from the forces between that shoulder and the other hand. They are asking for the magnitude that these two torques have (each).
 
  • #5
Is my result for R correct or should I include the other arm in the calculation (so the forces would be 2 x W/2, 2 x Warm, 2 x R and W)?
 

Related to Force and momentum in gymnastics position

What is force and momentum in gymnastics position?

Force and momentum in gymnastics position refer to the physical principles that govern the movement and stability of a gymnast's body while performing various skills and routines. Force refers to the push or pull that is exerted on an object, while momentum is the amount of motion an object has.

How does force and momentum affect a gymnast's performance?

Force and momentum play a crucial role in a gymnast's performance as they are necessary for generating power, executing skills, and maintaining balance and control. The correct application of force and momentum can result in impressive tumbling passes, high-flying leaps, and graceful movements.

What are some examples of force and momentum in gymnastics?

Examples of force and momentum in gymnastics include the take-off and landing phases of a vault, the swinging motion on the uneven bars, and the rotation of the body during a floor routine. Each of these skills requires the correct application of force and momentum to be executed successfully.

How can a gymnast increase their force and momentum?

A gymnast can increase their force and momentum by improving their strength, flexibility, and technique. Strength training exercises, such as weightlifting and bodyweight exercises, can help increase the force that a gymnast can generate. Similarly, improving flexibility allows a gymnast to use their full range of motion, resulting in more powerful movements. Proper technique, such as using proper body positioning and timing, also plays a crucial role in maximizing force and momentum.

How can a gymnast maintain control over their force and momentum?

To maintain control over their force and momentum, a gymnast must have good body awareness and control. This means being able to anticipate and adjust to the forces acting on their body during a skill. Building core strength, practicing drills and progressions, and receiving proper coaching can all help a gymnast develop better control over their force and momentum.

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