CP BIO Whiplash Injuries. When a car is hit from behind, its passengers undergo sudden forward acceleration, which can cause a severe neck injury known as whiplash. During normal acceleration, the neck muscles play a large role in accelerating the head so that the bones are not injured. But during a very sudden acceleration, the muscles do not react immediately because they are flexible; most of the accelerating force is provided by the neck bones. Experiments have shown that these bones will fracture if they absorb more than 8.0 J of energy, (a) If a car waiting at a stoplight is rear-ended in a collision that lasts for 10.0 ms, what is the greatest speed this car and its driver can reach without breaking neck bones if the driver’s head has a mass of 5.0 kg (which is about right for a 70-kg person)? Express your answer in m/s and in mi/h. (b) What is the acceleration of the passengers during the collision in part (a), and how large a force is acting to accelerate their heads? Express the acceleration in m/s2 and in g s.
Want to see the full answer?
Check out a sample textbook solutionChapter 6 Solutions
University Physics (14th Edition)
Additional Science Textbook Solutions
The Cosmic Perspective Fundamentals (2nd Edition)
An Introduction to Thermal Physics
College Physics
Introduction to Electrodynamics
Essential University Physics: Volume 2 (3rd Edition)
Essential University Physics: Volume 1 (3rd Edition)
- A 5 kg box rests on a tabletop. On one side, it compresses a spring with a stiffness of 1000 N/m by 1 cm. If the friction force cancels out the force of the spring what must be the minimum coefficient of static friction between the box and table to keep the box from moving?arrow_forwardYou are a bully. You pin a 48 kg dweeb to a wall so that his feet aren't touching the ground. Your arm is extended so that it makes an angle 28 degrees with the horizontal. The dweeb's back is so sweaty with fear that there is no friction between his back and the wall. What is the magnitude of the force , in N, you must apply to keep the dweeb in equilibrium? (Use g = 10 m/s2) This scenario is represented schematically below. Unfortunately for you, years later the dweeb is your boss and he makes your life miserable. (Please answer to the fourth decimal place - i.e 12.3445)arrow_forwardThe Harrier Jump Jet is a fixed wing military jet designed for vertical takeoff and landing (VTOL). It is capable of rotating its jets from a horizontal to a vertical orientation in order to takeoff, land and conduct horizontal maneuvers. Determine the vertical thrust required to accelerate an 8600-kg Harrier upward at 0.40 m/s/s.arrow_forward
- 0.00% Correct! Problem 3: Block B is set on the wedge A and released from rest. Assume all surfaces of contact are smooth (both between A and B, and between A and the supporting surface C). Take mµ = 36 kg, mß = 6 kg, and 0 - 45⁰. a A ↑ MA MB OBIA g=9.81m/s² Your Answer: The acceleration of B with respect to A is given by aß/A: 7.537 m/s² Correct Answer: The acceleration of B with respect to A is given by aB/A: 7.47E+000 m/s²arrow_forwardBank robbers have pushed a 1000 kg safe to a second-story floor-to-ceiling window. They plan to break the window, then lower the safe 3.0 m to their truck. Not being too clever, they stack up 500 kg of furniture, tie a rope between the safe and the furniture, and place the rope over a pulley. Then they push the safe out the window. The problem was that the acceleration was too large and the safe slammed on the truck withlarge velocity (6.1 m/s), breaking through the truck floor.Now the robbers decide they learned their lesson. They plan to redo this action and decide that thesafe should not hit the (new) truck with velocity greater than 1.5 m/s.What is the maximum acceleration that the safe can have in order to limit the impact velocity to1.5 m/s? What is the minimum coefficient of friction that they need to have this work?arrow_forwardBank robbers have pushed a 1000 kg safe to a second-story floor-to-ceiling window. They plan to break the window, then lower the safe 3.0 m to their truck. Not being too clever, they stack up 500 kg of furniture, tie a rope between the safe and the furniture, and place the rope over a pulley. Then they push the safe out the window. The problem was that the acceleration was too large and the safe slammed on the truck withlarge velocity (6.1 m/s), breaking through the truck floor.Now the robbers decide they learned their lesson. They plan to redo this action and decide that thesafe should not hit the (new) truck with velocity greater than 1.5 m/s.What is the maximum acceleration that the safe can have in order to limit the impact velocity to1.5 m/s?arrow_forward
- Bank robbers have pushed a 1000 kg safe to a second-story floor-to-ceiling window. They plan to break the window, then lower the safe 3.0 m to their truck. Not being too clever, they stack up 500 kg of furniture, tie a rope between the safe and the furniture, and place the rope over a pulley. Then they push the safe out the window. The problem was that the acceleration was too large and the safe slammed on the truck withlarge velocity (6.1 m/s), breaking through the truck floor.Now the robbers decide they learned their lesson. They plan to redo this action and decide that thesafe should not hit the (new) truck with velocity greater than 1.5 m/s.What is the maximum acceleration that the safe can have in order to limit the impact velocity to1.5 m/s? Draw a sketch using the free body diagram of each step.arrow_forwardThe engines of a tanker broke down and the wind pushes the ship with a constant speed of 1.5 m / s straight towards a reef. When the boat is 500 m from the reef, the wind stops and the engineer manages to start the engines. The rudder is stuck, so the only option is to try to accelerate backwards. The mass of the ship and its cargo is 3.6 x 107 kg and the engines produce a net horizontal force of 8 x 104 N. The hull can withstand impacts at a speed of 0.2 m / s or less. The retarding force that the water exerts on the hull of the ship can be neglected. a) The equation of motion that corresponds to the horizontal component is? b)The acceleration of the ship is equal to? c) If the reef does not exist, the vessel, before stopping, travels what distance?arrow_forwardA desperate hiker has to think fast to help his friend who has fallen below him. Quickly, he ties a rope to a rock of mA = 405 kg and makes his way over the ledge (see the figure below). If the coefficient of static friction between the rock and the ground is H=0.348, and the mass of the hiker is ma= 70.1 kg, what is the maximum mass of the friend, mc, that the rock can hold so the hikers can then make their way up over the ledge? Assume the rope is parallel to the ground and the point where the rope passes over the ledge is frictionless. (ANS: 70.8 kg)arrow_forward
- A 80.0 kg skater with the Birmingham Bulls hockey team with an initial speed of 7.8 m/s stops propelling himself and begins to coast across the ice, eventually coming to rest. The coefficient of kinetic friction between the ice and the skate blades is 0.100, and air resistance can be neglected. How far will the skater travel before coming to rest?arrow_forwardPhysics The lock down has made mellisa soft. She gets caught the last time she tries to steal a box of red vines, so mallisa decides she needs to start working out. Since gyms are so expensive, mallisa decides to practice pushing a 100 kg box filled with chemistry textbooks place of red vines) across her living room and back, a distance of 30 m. If mellisa pushes with a force of 875 N at an angle 25 degrees below the horizontal, what was the amount of work that mellisa performed on the box? a)-23.800J b) -13,600J c)31,200J d) 23,800Jarrow_forwardA 10 m long vertical cannon is used to accelerate a 1.0 kg ball straight up into air. A constant force of 13.2N is used to access bowling ball length of the canon. what is the ball's approximate velocity as it leaves the canon assuming no energy loss to frictionarrow_forward
- College PhysicsPhysicsISBN:9781305952300Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningUniversity Physics (14th Edition)PhysicsISBN:9780133969290Author:Hugh D. Young, Roger A. FreedmanPublisher:PEARSONIntroduction To Quantum MechanicsPhysicsISBN:9781107189638Author:Griffiths, David J., Schroeter, Darrell F.Publisher:Cambridge University Press
- Physics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningLecture- Tutorials for Introductory AstronomyPhysicsISBN:9780321820464Author:Edward E. Prather, Tim P. Slater, Jeff P. Adams, Gina BrissendenPublisher:Addison-WesleyCollege Physics: A Strategic Approach (4th Editio...PhysicsISBN:9780134609034Author:Randall D. Knight (Professor Emeritus), Brian Jones, Stuart FieldPublisher:PEARSON