Basic Biomechanics
7th Edition
ISBN: 9780073522760
Author: Susan J Hall
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 13, Problem 4AP
A hand exerts a force of 90 N on a scale at 32 cm from the joint center at the elbow. If the triceps attach to the ulna at a 90° angle and at a distance of 3 cm from the elbow joint center, and if the weight of the forearm and hand is 40 N with the hand/forearm CG located 17 cm from the elbow joint center, how much force is being exerted by the triceps? (Answer: 733.3 N)
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The adjacent diagram displays the joint reaction force between the acetabulum and femoral head for the right leg during single leg stance. Also shown are the abductor muscle force (AMF), the weight of the body above the level of the stance hip (W) and their corresponding moment arms with respect to the joint centre (D and D1). If the right leg weighs 1/6 of total body weight, the ratio of D1 to D is 2.4, and AMF is angled at 30 degrees relative to the vertical, calculate the:
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Briefly explain why.
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The three main forces that act on the patella are shown on
the diagram of the knee joint below. These forces are the
quadriceps muscle force (FQ), the patella ligament force
(FPL), and the patellofemoral joint reaction force (FPF). The
angles a and ẞ are with respect to a line that is
perpendicular to FPF. Assuming a = 15°, ẞ = 20°, and FQ =
3725 N, use equations for static equilibrium to calculate (a)
FPL, and (b) FPF. (Hint: To solve this problem consider using
a coordinate system that is aligned with the principal axes
of the patella instead of the usual vertical and horizontal
axes). (c) Many people assume FQ and FPL are always equal
in magnitude but this is only true under certain
circumstances. Under what conditions are FQ and FPL equal
in magnitude?
Fo
FPF
FP B
GriffithUNIVERSITY
Queensland Australia
Chapter 13 Solutions
Basic Biomechanics
Ch. 13 - Why does a force directed through an axis of...Ch. 13 - Why does the orientation of a force acting on a...Ch. 13 - A 23-kg boy sits 1.5 m from the axis of rotation...Ch. 13 - Prob. 4IPCh. 13 - Two people push on opposite sides of a swinging...Ch. 13 - Prob. 6IPCh. 13 - Prob. 7IPCh. 13 - Prob. 8IPCh. 13 - A 10-kg block sits motionless on a table in spite...Ch. 13 - Prob. 10IP
Ch. 13 - A 35-N hand and forearm are held at a 45 angle to...Ch. 13 - A hand exerts a force of 90 N on a scale at 32 cm...Ch. 13 - A patient rehabilitating a knee injury performs...Ch. 13 - A worker leans over and picks up a 90-N box at a...Ch. 13 - A man carries a 3 m, 32-N board over his shoulder....Ch. 13 - A therapist applies a lateral force of 80 N to the...Ch. 13 - Tendon forces Ta and Tb are exerted on the...
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