1. The hip is stabilized, in part, by the gluteus medius muscle. Figure (a) represents a person standing on one leg and shows the hip as an inverted trapezoid, the femur as two line segments representing the neck and shaft, and a single line segment representing the hip muscle (red line). Figure (b) changes the scale in order to see the force components more easily, including a vector for the body's weight (W) and another for the muscle force needed to balance the hip (M). The femur connection with the hip is a ball-and-socket joint and is the location of the pivot in this model. Figure (c) shows the weight and muscle forces translated to a single lever arm where the pivot is the ball-and-socket joint. a) www.timvandevall.com b) M N W Assume all quantities are correct to 2 significant figures. Enter to 2 significant figures M = c) a) When standing on one leg, 5/6 of a person's weight is applied at the body's center of mass, as shown in the diagram. The other 1/6 is the mass of the leg on which the person is balancing; therefore, that part of the mass does not affect the torque. If a person's total mass is 89 kg, then what magnitude of force (in Newtons) must the gluteus medius provide to keep the hips level? Assume the distance from M to the pivot is 7 cm and the distance from W to the pivot is 15 cm. b) Calculate the magnitude of the joint reaction force at the pivot. M W www.timvandevall.com a) When standing on one leg, 5/6 of a person's weight is applied at the body's center of mass, as shown in the diagram. The other 1/6 is the mass of the leg on which the person is balancing; therefore, that part of the mass does not affect the torque. If a person's total mass is 89 kg, then what magnitude of force (in Newtons) must the gluteus medius provide to keep the hips level? Assume the distance from M to the pivot is 7 cm and the distance from W to the pivot is 15 cm. Assume all quantities are correct to 2 significant figures. Enter to 2 significant figures M = N b) Calculate the magnitude of the joint reaction force at the pivot. Enter to 2 significant figures J= N c) If the gluteus medius is weak, what effect might that have on the hip when a person stands on one leg? A. The muscle may not support the weight and the person may lose balance B. Other muscles might have to support the weight more causing increased strain or pain. C. Choices A. and B.

1. The hip is stabilized, in part, by the gluteus medius muscle. Figure (a) represents a person standing on one leg and shows the hip as an inverted trapezoid, the femur as two line segments representing the neck and shaft, and a single line segment representing the hip muscle (red line). Figure (b) changes the scale in order to see the force components more easily, including a vector for the body's weight (W) and another for the muscle force needed to balance the hip (M). The femur connection with the hip is a ball-and-socket joint and is the location of the pivot in this model. Figure (c) shows the weight and muscle forces translated to a single lever arm where the pivot is the ball-and-socket joint. a) www.timvandevall.com b) M N W Assume all quantities are correct to 2 significant figures. Enter to 2 significant figures M = c) a) When standing on one leg, 5/6 of a person's weight is applied at the body's center of mass, as shown in the diagram. The other 1/6 is the mass of the leg on which the person is balancing; therefore, that part of the mass does not affect the torque. If a person's total mass is 89 kg, then what magnitude of force (in Newtons) must the gluteus medius provide to keep the hips level? Assume the distance from M to the pivot is 7 cm and the distance from W to the pivot is 15 cm. b) Calculate the magnitude of the joint reaction force at the pivot. M W www.timvandevall.com a) When standing on one leg, 5/6 of a person's weight is applied at the body's center of mass, as shown in the diagram. The other 1/6 is the mass of the leg on which the person is balancing; therefore, that part of the mass does not affect the torque. If a person's total mass is 89 kg, then what magnitude of force (in Newtons) must the gluteus medius provide to keep the hips level? Assume the distance from M to the pivot is 7 cm and the distance from W to the pivot is 15 cm. Assume all quantities are correct to 2 significant figures. Enter to 2 significant figures M = N b) Calculate the magnitude of the joint reaction force at the pivot. Enter to 2 significant figures J= N c) If the gluteus medius is weak, what effect might that have on the hip when a person stands on one leg? A. The muscle may not support the weight and the person may lose balance B. Other muscles might have to support the weight more causing increased strain or pain. C. Choices A. and B.

Glencoe Physics: Principles and Problems, Student Edition

1st Edition

ISBN:9780078807213

Author:Paul W. Zitzewitz

Publisher:Paul W. Zitzewitz

Chapter5: Displacement And Force In Two Dimensions

Section: Chapter Questions

Problem 82A

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