Concept explainers
The Achilles tendon connects the muscles in your calf to the back of your foot. When you are sprinting, your Achilles tendon alternately stretches, as you bring your weight down onto your forward foot, and contracts to push you off the ground. A 70 kg runner has an Achilles tendon that is 15 cm long and has a cross-section area of 110 mm2, typical values for a person of this size.
a. By how much will the runner’s Achilles tendon stretch if the maximum force on it is 8.0 times his weight, a typical value while running?
b. What fraction of the tendon’s length does this correspond to?
Want to see the full answer?
Check out a sample textbook solutionChapter 8 Solutions
College Physics: A Strategic Approach (4th Edition)
Additional Science Textbook Solutions
Lecture- Tutorials for Introductory Astronomy
An Introduction to Thermal Physics
Applied Physics (11th Edition)
University Physics with Modern Physics (14th Edition)
Conceptual Integrated Science
Life in the Universe (4th Edition)
- Your answer is partially correct. African elephants are the largest land animals. They consume approximately 10% of their body weight in food each day, which for an adult male, can be 1000 lb. of vegetation! Their diet consists mostly of grasses, bamboo, tree bark, and fruit. They also like to dine on tree leaves. To reach them, they often stand up on their hind legs and extend their trunks (see the figure). The elephant in the figure is in equilibrium. The location of the elephant's center of mass is shown, and the axis of rotation has been chosen to correspond to the hip joint. The forces in the elephant's free-body diagram are shown, and there is a static friction force between the elephant's back feet and the ground. Use the following information and calculate the magnitude of the tension in the elephant's trunk T (m = 4540 kg, FN = 'fs=133 cm, rcg = 76.0 cm, r = 229 cm). Number 1103.035 +x Axis of rotation Units N 165⁰ 60⁰ W =FN 30° FN 10° Michael Poliza/Caters News Agencyarrow_forwardA glass optical fiber in a communications system has a diameter of 9.0 μm.a. What maximum tension could this fiber support without breaking?b. Assume that the fiber stretches in a linear fashion until the instant it breaks. By how much will a 10-m-long fiber have stretched when it is at the breaking point?arrow_forwardWhat is T?arrow_forward
- The uniform beam has a mass of 46 kg per meter of length. Determine the reactions at the supports. A umber of significant digits is 3. The tolerance is ± 1 in the nificant digit. A₂= i Bio By= 2.9 m i N !N N 1.4 m- 300 kg Barrow_forwardConsider a nanotube with a Youngs modulus of 2.130 1012 N/m2 that experiences a tensile stress of 5.3 1010 N/m2. Steel has a Youngs modulus of about 2.000 1011 Pa. How much stress would cause a piece of steel to experience the same strain as the nanotube?arrow_forwardAfrican elephants are the largest land animals. They consume approximately 10% of their body weight in food each day, which for an adult male, can be 1000 lb. of vegetation! Their diet consists mostly of grasses, bamboo, tree bark, and fruit. They also like to dine on tree leaves. To reach them, they often stand up on their hind legs and extend their trunks (see the figure). The elephant in the figure is in equilibrium. The location of the elephant's center of mass is shown, and the axis of rotation has been chosen to correspond to the hip joint. The forces in the elephant's free-body diagram are shown, and there is a static friction force between the elephant's back feet and the ground. Use the following information and calculate the magnitude of the tension in the elephant's trunk T (m = 4540 kg, FN = rfs = 133 cm, rcg = 76.0 cm, r = 229 cm). Number +x Axis of rotation Units 60 165 30 W TTFN cg 10° Michael Poliza/Caters News Agencyarrow_forward
- A 40.0-m-long steel elevator cable has a cross-sectional area of 4.0 × 10^(-4 )m^2and is able to stretch 1.0 cm before breaking. If the elevator itself has a mass of1000. kg, how many 70.0-kg people can safely ride in the elevator?(Ysteel = 2.0 × 10^ 11 N/m^2) a. 14 b. 16 c. 12 d. 18 e. NOTAarrow_forwardWhen 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?arrow_forwardA clever witch is social distancing during trick-or-treating by sticking her pumpkin-shaped bucket full of candy on the end of her broomstick. Her broomstick has a length of L = 1.7 m and she holds it horizontally. The broomstick has a mass of 0.80 kg and the pumpkin has a mass of 2.3 kg. The witch holds her hands a distance of d = 0.40 m apart. L What is the force from the hand on the end of the broom? This is the hand on the left in the figure. 1 5.27 FL = X N d What is the force from the hand closer to the middle of the broom? This is the hand on the right in the figure. 2 N FR = Submit Answer View Previous Question Question 4 of 6 View Next Questionarrow_forward
- A particular human hair has a Young's modulus of 3.31 x 10° N/m2 and a diameter of 145 um. If a 236 g object is suspended by the single strand of hair that is originally 17.5 cm long, by how much AL bair will the hair AL hair = m stretch? If the same object were hung from an aluminum wire of the same dimensions as the hair, by how much ALAI would the ALA = aluminum stretch? If the strand of hair is modeled as a spring, what is its spring N/m constant khair? khair =arrow_forwardA 0.600-mm diameter wire stretches 0.500% of its length when it is stretched with a tension of 20.0 N. What is the Young's modulus of this wire? O 3.54 x 109 N/m² O 5.66 x 1010 N/m2 O 2.78 x 109 N/m? O 1.41 x 1010 N/m² O 6.43 x 109 N/m2arrow_forwardA 46 kg ball is suspended from a steel wire of length 4.0 m and radius 2.0 mm. By how much does the wire stretch? mm eBookarrow_forward
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning