College Physics: A Strategic Approach (3rd Edition)
3rd Edition
ISBN: 9780321879721
Author: Randall D. Knight (Professor Emeritus), Brian Jones, Stuart Field
Publisher: PEARSON
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Question
Chapter 8, Problem 20MCQ
To determine
To find: The force required to exert by the tendon to keep the leg in the given position.
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Students have asked these similar questions
When you bend your knee, the quadriceps muscle is stretched. This increases the tension in the quadriceps tendon attached to your kneecap (patella), which, in turn, increases the tension in the patella tendon that attaches your kneecap to your lower leg bone (tibia). Simultaneously, the end of your upper leg bone (femur) pushes outward on the patella. Shown is how these parts of a knee joint are arranged. What size force does the femur exert on the kneecap if the tendons are oriented as in the figure and the tension in each tendon is 60 N?
When you carry shopping bags, rather than grasp the handles with your hand as in Q8.14a, you might choose to put them over your arm and slide the handle toward your elbow as in Q8.14b. Explain why this leads to less muscle effort to carry the bags and less force in your elbow joint.
Triceps
14-
101
2.4 cm
Muscles can only contract, so they occur in pairs. In the arm, the biceps muscle is a flexor-that is, it
closes the limb. The triceps muscle is an extensor that opens the limb. This configuration is typical of
skeletal muscles, bones, and joints in humans and other vertebrates. Most skeletal muscles exert
much larger forces within the body than the limbs apply to the outside world. Imagine that a person
is pushing down on a tabletop with their hand as shown in the figure. If the person applies a
downward force of 70 N with their hand (thats about 16 lbs of force) what force does the triceps
tendon exert on the lower arm? The unknown force is indicated by the red arrow in the figure. Ignore
the weight of the arm in your calculation.
O 5.6 N
70 N
280 N
875 N
30 cm
945 N
Chapter 8 Solutions
College Physics: A Strategic Approach (3rd Edition)
Ch. 8 - An object is acted upon by two (and only two)...Ch. 8 - Prob. 2CQCh. 8 - Could a ladder on a level floor lean against a...Ch. 8 - If you are using a rope to raise a tall mast,...Ch. 8 - Prob. 5CQCh. 8 - Prob. 6CQCh. 8 - Prob. 7CQCh. 8 - A spring exerts a 10 N force after being stretched...Ch. 8 - The left end of a spring is attached to a wall....Ch. 8 - A spring is attached to the floor and pulled...
Ch. 8 - A typical mattress has a network of springs that...Ch. 8 - Take a spring and cut it in half to make two...Ch. 8 - A wire is stretched right to its breaking point by...Ch. 8 - Steel nails are rigid and unbending. Steel wool is...Ch. 8 - The rod in Figure Q8.15 pivots around an axle at...Ch. 8 - Two children hold opposite ends of a lightweight,...Ch. 8 - Prob. 17MCQCh. 8 - Prob. 18MCQCh. 8 - Prob. 19MCQCh. 8 - Prob. 20MCQCh. 8 - Prob. 21MCQCh. 8 - Prob. 22MCQCh. 8 - You have a heavy piece of equipment hanging from a...Ch. 8 - Prob. 24MCQCh. 8 - Prob. 1PCh. 8 - Prob. 2PCh. 8 - Prob. 3PCh. 8 - Prob. 4PCh. 8 - Youre carrying a 3.6-m-long, 25 kg pole to a...Ch. 8 - Prob. 6PCh. 8 - How much torque must the pin exert to keep the rod...Ch. 8 - Prob. 8PCh. 8 - Prob. 9PCh. 8 - Consider the procedure for measuring a womans...Ch. 8 - Prob. 11PCh. 8 - Prob. 12PCh. 8 - Prob. 13PCh. 8 - Prob. 14PCh. 8 - Prob. 15PCh. 8 - Prob. 16PCh. 8 - Prob. 17PCh. 8 - The stability of a vehicle is often rated by the...Ch. 8 - You want to slowly push a stiff board across a 20...Ch. 8 - Prob. 20PCh. 8 - A car manufacturer claims that you can drive its...Ch. 8 - Prob. 22PCh. 8 - One end of a spring is attached to a wall. A 25 N...Ch. 8 - An orthodontic spring, connected between the upper...Ch. 8 - Experiments using optical tweezers measure the...Ch. 8 - A spring has an unstretched length of 10 cm. It...Ch. 8 - One end of a 10-cm-long spring is attached to the...Ch. 8 - A spring stretches 5.0 cm when a 0.20 kg block is...Ch. 8 - A 1.2 kg block is hung from a vertical spring,...Ch. 8 - You need to make a spring scale to measure the...Ch. 8 - A force stretches a wire by 1.0 mm. a. A second...Ch. 8 - What hanging mass will stretch a 2.0-m-long,...Ch. 8 - How much force does it take to stretch a...Ch. 8 - An 80-cm-long, 1.0-mm-diameter steel guitar string...Ch. 8 - A student is testing a 1.0 m length of...Ch. 8 - A 1.2-m-long steel rod with a diameter of 0.50 cm...Ch. 8 - A mineshaft has an ore elevator hung from a single...Ch. 8 - The normal force of the ground on the foot can...Ch. 8 - A three-legged wooden bar stool made out of solid...Ch. 8 - Prob. 40PCh. 8 - A glass optical fiber in a communications system...Ch. 8 - The Achilles tendon connects the muscles in your...Ch. 8 - Prob. 43GPCh. 8 - Prob. 44GPCh. 8 - Using the information in Figure 8.2, calculate the...Ch. 8 - A woman weighing 580 N does a pushup from her...Ch. 8 - Prob. 47GPCh. 8 - Prob. 48GPCh. 8 - Prob. 49GPCh. 8 - The wheel of mass m in Figure P8.50 is pulled on...Ch. 8 - A 5.0 kg mass hanging from a spring scale is...Ch. 8 - Two identical, side-by-side springs with spring...Ch. 8 - Two springs have the same equilibrium length but...Ch. 8 - Figure P8.54 shows two springs attached to a block...Ch. 8 - A 60 kg student is standing atop a spring in an...Ch. 8 - A 25 kg child bounces on a pogo stick. The pogo...Ch. 8 - Figure P8.57 shows a lightweight plank supported...Ch. 8 - In the hammer throw, an athlete spins a heavy mass...Ch. 8 - There is a disk of cartilage between each pair of...Ch. 8 - In Example 8.1, the tension in the biceps tendon...Ch. 8 - Larger animals have sturdier bones than smaller...Ch. 8 - Orb spiders make silk with a typical diameter of...Ch. 8 - Prob. 63MSPPCh. 8 - Prob. 64MSPPCh. 8 - Prob. 65MSPP
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