Concept explainers
Integrated Concepts
Suppose we replace the 4.0-kg book in Exercise 9.31 of the biceps muscle with an elastic exercise rope that obeys Hooke's Law. Assume its force constant
Want to see the full answer?
Check out a sample textbook solutionChapter 9 Solutions
College Physics for AP Courses
Additional Science Textbook Solutions
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
College Physics: A Strategic Approach (4th Edition)
College Physics: A Strategic Approach (3rd Edition)
Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)
- We analyzed the biceps muscle example with the angle between forearm and upper arm set at 90°. Using the same numbers as in Example 9.4, find the force exerted by the biceps muscle when the angle is 120° and the forearm is in a downward position.arrow_forwardUnlike most of the other muscles in our bodies, the masseter muscle in the jaw, as illustrated in Figure 9.44, is attached relatively far from the joint, enabling large forces to be exerted by the back teeth. (a) Using the information in the figure, calculate the force exerted by the lower teeth on the bullet. (b) Calculate the force on the joint.arrow_forwardCheck Your Understanding A 2.0-m-long wire stretches 1.0 mm when subjected to a load. What is the tensile strain in the wire?arrow_forward
- In order to get his car out of the mud, a man ties one end of a rope to the front bumper and the other end to a tee 15 m away as shown below. He then pulls on the center of the rope with a force of 400 N, which causes its center to be displaced 0.30 m, as shown. What is the force of the rope on the car?arrow_forwarda) What is the mechanical advantage of a wheelbarrow, such as the one in Figure 9.24, if the center of gravity of the wheelbarrow and its load has a perpendicular lever arm of 5.50 cm, while the hands have a perpendicular lever arm of 1.02 m? (b) What upward force should you exert to support the wheelbarrow and its load if their combined mass is 55.0 kg? (c) What force does the wheel exert on the ground? Figure 9.24 (a) In the case of the wheelbarrow, the output force or load is between the pivot and the input force. The pivot IS the wheel's axle. Here, the output force is greater than the input force. Thus, a wheelbarrow enables you to lift much heavier loads than you could with your body alone. (b) In the case of the shovel, the input force is between the pivot and the load, but the input lever arm is shorter than the output lever arm. The pivot is at the handle held by the right hand. Here, the output force (supporting the shovel's load) is less than the input force (from the hand nearest the load), because the Input is exerted closer to the pivot than is the outputarrow_forward(a) What force should the woman in Figure 9.45 exert on the floor with each hand to do a push-up? Assume that she moves up at a constant speed. (b) The triceps muscle at the back of her upper arm has an effective lever arm of 1.75 cm, and she exerts force on the floor at a horizontal distance of 20.0 cm from the elbow joint. Calculate the magnitude of the force in each triceps muscle, and compare it to her weight. (c) How much work does she do if her center of mass rises 0.240 m? (d) What is her useful power output if she does 25 pushups in one minute?arrow_forward
- (a) What minimum coefficient of friction is needed between the legs and the ground to keep the sign in Figure 9.35 in the position shown if the chain breaks? (b) What force is exerted by each side on the hinge?arrow_forwardWe analyzed the biceps muscle example with the angle between forearm and upper arm set at 90º . Using the same numbers as in figure shown , find the force exerted by the biceps muscle when the angle is 120º and the forearm is in a downward position.arrow_forwardSuppose we replace the 4.0-kg book of the biceps muscle with an elastic exercise rope that obeys Hooke’s Law. Assume its force constant k = 600 N/m. (a) How much is the rope stretched (past equilibrium) to provide the same force FB as in this example? Assume the rope is held in the hand at the same location as the book. (b) What force is on the biceps muscle if the exercise rope is pulled straight up so that the forearm makes an angle of 25º with the horizontal? Assume the biceps muscle is still perpendicular to the forearm.arrow_forward
- In the figure below, the biceps muscle exerts a force supporting a perpendicular forearm and a book. Suppose we replace the book with an elastic exercise rope that obeys Hooke's Law. Assume its force constant k = 453 N/m. Triceps muscle Biceps U muscle PHYSICS m, = 4.3 kg CG FE m, = 3.7 kg Wo CG 4.0 cml Wa 16 cm 38 cm (a) How much is the rope stretched (past equilibrium) to provide the same force w, as before the book was replaced? Assume the rope is held in the hand at the same location as the book. (Enter your answer in cm.) |cm (b) What force (in N) is on the biceps muscle if the exercise rope is pulled straight up so that the forearm makes an angle of 18° with the horizontal? Assume the biceps muscle is still perpendicular to the forearm. (Assume the same stretch in the rope as part (a). Enter the magnitude.)arrow_forwardExplain how dumbbell curls (flexing the elbow while holding dumbbells) with (A) the forearms supinated and (B) the forearms pronated signifncalty alter the demands placed on the elbow flexors. Mention the muscles involved in your answer. Edit View Insert Format Tools Table 12pt v Paragraph v |BIU A ev T? v :arrow_forwardHER A man holds a 175-N ball in his hand, with the forearm horizontal (see the drawing). He can support the ball in this position because of the flexor muscle force M, which is applied perpendicular to the forearm. The forearm weighs 21.4 N and has a center of gravity as indicated. Upper am bone Flexor muscle cing fc Elbow joint 89) 00510 m r 0.0890 m 0.330 m- (a) Find the magnitude of M 1149 X N (b) Find the magnitude and direction of the force applied by the upper arm bone to the forearm at the elbow joint. magnitude direction downward Additional Materials Book ??TO MacBook Ait 7.arrow_forward
- College PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax CollegeUniversity Physics Volume 1PhysicsISBN:9781938168277Author:William Moebs, Samuel J. Ling, Jeff SannyPublisher:OpenStax - Rice UniversityPhysics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningGlencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-Hill