Concept explainers
You’re an expert witness in a medical malpractice lawsuit. A hospital patient’s leg slipped off a stretcher and his heel hit the floor. The defense attorney for the hospital claims the leg, with mass 8 kg, hit the floor with a force equal to the weight of the leg—about 80 N—and any damage was due to a prior injury. You argue that the leg and heel dropped freely for 0.7 m, then hit the floor and stopped in 2 cm. What do you tell the jury about the force on the heel?
Want to see the full answer?
Check out a sample textbook solutionChapter 6 Solutions
Modified Mastering Physics With Pearson Etext -- Standalone Access Card -- For Essential University Physics (3rd Edition)
Additional Science Textbook Solutions
Conceptual Integrated Science
Physics for Scientists and Engineers with Modern Physics
Tutorials in Introductory Physics
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
College Physics (10th Edition)
The Cosmic Perspective (8th Edition)
- Two rigid bodies, A and B, both 1 kg in mass, are connected by a linear spring with a spring constant of 0.2 N/m. Initially, the spring is unstretched and the bodies are at rest. If multiple forces and moments are applied to the two bodies that result in the speed of body A increasing to 10 m/s, the speed of body B increasing to 4 m/s, and the stretch of the spring increasing by 10 m, then -20 Nm of work was done by the spring on the body A, B system. Two rigid bodies, A and B, both 1 kg in mass, are connected by a linear spring with a spring constant of 0.2 N/m. Initially, the spring is unstretched and the bodies are at rest. If multiple forces and moments are applied to the two bodies that result in the speed of body A increasing to 10 m/s, the speed of body B increasing to 4 m/s, and the stretch of the spring increasing by 10 m, then -20 Nm of work was done by the spring on the body A, B system. True Falsearrow_forwardAn 85 kg man stands in a very strong wind moving at 14 m/s at torso height. As you know, he will need to lean in to the wind, and we can model the situation to see why. Assume that the man has a mass of 85 kg, with a center of gravity 1.0 m above the ground. The action of the wind on his torso, which we approximate as a cylinder 50 cm wide and 90 cm long centered 1.2 m above the ground, produces a force that tries to tip him over backward. To keep from falling over, he must lean forward. a. What is the magnitude of the torque provided by the wind force? Take the pivot point at his feet. Assume that he is standing vertically.b. At what angle to the vertical must the man lean to provide a gravitational torque that is equal to this torque due to the wind force?arrow_forwardA sledgehammer of mass m = 1.9 kg falls freely vertically downward from a height of h = 2.5 m at an initial speed of v = 6.5 m/s before striking a partially buried piling. After the blow the piling has moved d = 0.075 m deeper. How much force, in newtons, was applied to the piling? Assume all the energy goes towards driving the piling into the ground, and the force of the sledgehammer is constant over the distance d that the piling is driven into the ground. Note that you can ignore the change in potential energy of the piling itself. Further, because d is so small compared to h, you can also ignore the change in potential energy of the hammer as well as it moves distance d.arrow_forward
- In a railroad accident, a boxcar weighing 200 kN and traveling at 2.00 m/s on horizontal track slams into a stationary caboose weighing 440 kN. The collision connects the caboose to the boxcar. How much energy is transferred from kinetic energy to other forms of energy in the collision?arrow_forwardHow much gravitational potential energy (in J) (relative to the ground on which it is built) is stored in an Egyptian pyramid, given its mass is about 8 ✕ 109 kg and its center of mass is 37.0 mabove the surrounding ground? J (b) What is the ratio of this energy to the daily food intake of a person (1.2 ✕ 107 J)?arrow_forwardWhen a click beetle is upside down on its back, it jumps upward by suddenly arching its back, transferring energy stored in a muscle to mechanical energy.This launching mechanism produces an audible click, giving the beetle its name.Videotape of a certain clickbeetle jump shows that a beetle of mass m = 4.0 * 10-6 kg moved directly upward by 0.77 mm during the launch and then to a maximum height of h= 0.30 m. During the launch, what are the average magnitudes of (a) the external force on the beetle’s back from the floor and (b) the acceleration of the beetle in terms of g?arrow_forward
- A man stands on his toes by exerting an upward force through the Achilles tendon, as in the figure. Calculate the force in the Achilles tendon if he stands on one foot and has a mass of 80kg.arrow_forwardIf you are driving home from school and have to slam on the brakes to avoid hitting a car that merged into your lane without looking, what happens to your car’s kinetic energy as it comes to a rest?arrow_forwardHow much gravitational potential energy (in J) (relative to the ground on which it is built) is stored in an Egyptian pyramid, given its mass is about 6 ✕ 109 kg and its center of mass is 26.0 m above the surrounding ground? What is the ratio of this energy to the daily food intake of a person (1.2 ✕ 107 J)?arrow_forward
- Assume that the force of a bow on an arrow behaves like the spring force. In aiming the arrow, an archer pulls the drawstring back 62 cm from its rest position and holds it in position with a force of 170 N. If the mass of the arrow is 59 g and the "spring" is massless, what is the speed (in m/s) of the arrow immediately after it leaves the bow?arrow_forwardStarting from rest, a 92-kg firefighter slides down a fire pole. The average frictional force exerted on him by the pole has a magnitude of 710 N, and his speed at the bottom of the pole is 3.5 m/s. How far did he slide down the pole?arrow_forwardA 6 000-kg freight car rolls along rails with negligible friction. The car is brought to rest by a combination of two coiled springs as illustrated in Figure P6.27 (page 188). Both springs are described by Hookes law and have spring constants k1 = 1 600 N/m and k2, = 3 400 N/m. After the first spring compresses a distance of 30.0 cm, the second spring acts with the first to increase the force as additional compression occurs as shown in the graph. The car comes to rest 50.0 cm after first contacting the two-spring system. Find the cars initial speed.arrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningClassical Dynamics of Particles and SystemsPhysicsISBN:9780534408961Author:Stephen T. Thornton, Jerry B. MarionPublisher:Cengage Learning
- Physics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningUniversity Physics Volume 1PhysicsISBN:9781938168277Author:William Moebs, Samuel J. Ling, Jeff SannyPublisher:OpenStax - Rice UniversityGlencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-Hill