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387

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Mechanical Engineering

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Dec 6, 2023

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HSS 387 Basic Biomechanical Factors & Concepts: Self Study Worksheet Chapter 3 1 Important Terms and Concepts : Write the term or concept that best matches the definition. 1. A description of motion; includes consideration of time, displacement, velocity, acceleration, and space factors. 2. A force that is applied off center or in a direction not in line with the center of rotation of an object without a fixed axis; an applied force that is not in line with the object’s center of gravity. 3. The perpendicular distance between the location of force application and the axis 4. The study of mechanics as it relates to functional and anatomical analysis of biological systems 5. The study of systems that are in a constant state of motion or moving at a constant velocity without acceleration 6. The study of physical actions of forces; divided into statics and dynamics 7. The study of systems in motion with acceleration 8. The moment of force; turning effect of an eccentric force 9. The distance between the axis and the point of resistance application 10. The study of forces associated with the motion of a body Machines in the Body 1. List 3 reasons we utilize anatomical machines in the body a. ___________________________________________ b. ___________________________________________ c. ___________________________________________ 2. List the 4 functions of machines a. ___________________________________________ b. ___________________________________________ c. ___________________________________________ d. ___________________________________________

HSS 387 Basic Biomechanical Factors & Concepts: Self Study Worksheet Chapter 3 2 Lever Systems Fill in the blanks: In the human body, an anatomical lever is a machine used to increase or multiply the applied force, thus providing a _______________ when performing a task. The lever or rigid bar is represented anatomically by the _______________. The point of rotation about which the lever moves is represented by the _______________. When a muscle contracts, thus providing some _______________, the lever moves about its axis against some _______________. The arrangement and location of the _______________, _______________, and _______________ in relation to one another determine the type of lever and the application for which it is best suited. Complete the following : For each lever arrangement, list the order of the three points (axis, resistance application, and force application) and provide the lever’s function(s). Provide at least 2 examples for each lever class. Lever Class Lever Arrangement Functions Examples First Second Third Note : For 1 st Class levers, you should know when each function is applicable (i.e. with regards to the location of each component) Answer the following questions: 1. Anatomically, where is the point of force application? 2. If the resistance and resistance arm remain constant, and the force arm is made longer, what happens to the amount of force needed to move the resistance? 3. If the resistance arm is made longer, what happens to the amount of resistance that can be moved if the force and force arm are kept constant? 4. According to the Lever Equation, what happens to the force and/or force arm if either of the resistance components decreases?

HSS 387 Basic Biomechanical Factors & Concepts: Self Study Worksheet Chapter 3 3 5. For 1 st Class levers in which the goal is to balance the lever system, what happens if you decrease the length of the force arm? 6. For 2 nd Class levers, which is ALWAYS longer: the resistance arm or the force arm? What happens if you move the point of resistance farther away from the axis of rotation? 7. For 3 rd Class levers, which is ALWAYS longer: the resistance arm or the force arm? What happens if you move the point of force application closer to the axis? 8. What class of lever is the most common in the body? Complete the following table using the Lever and Mechanical Advantage Equations : Lever Components Variables Force Applied at Axis Placed at 25 Newtons of Resistance Placed at Lever Class FA RA Force MA A 0 8 16 B 13 0 18 C 19 9 6 D 15 2 7 Note : the resistance is 25 Newton Wheels & Axles : Fill in the blanks The function of wheels and axles is to enhance _______________ and _______________ in the musculoskeletal system. As such, they essentially function as a lever. The center of the wheel and axle serves as the _______________, whereas the radius of the wheel and axle serve as _______________. Force application to either the wheel or the axle will determine mechanical advantage. When force is applied to the wheel, and the radius of the wheel is greater than that of the axle, the _______________ has a mechanical advantage over the _______________. This allows a _______________ force to move a greater resistance applied to the axle. When the force is applied to the axle, the mechanical advantage results from the wheel turning a greater distance and speed, essentially functioning as a _______________ class lever.

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HSS 387 Basic Biomechanical Factors & Concepts: Self Study Worksheet Chapter 3 4 Pulley Systems : Answer the following questions . 1. What is the function of a single pulley system? Of a compound pulley system? 2. What is the mechanical advantage of a compound pulley system with 6 pulleys? 3. An example of an anatomical pulley system is the lateral malleolus and the tendon of peroneus longus. What happens when the peroneus longus muscle contracts? Name another pulley system found in the body. Laws of Motion and Factors Affecting Motion : Match the following definition to the appropriate term or concept. Word Bank: A. Balance B. Stability C. Center of Gravity D. Friction E. Static Friction F. Kinetic Friction G. Rolling Friction H. Equilibrium I. Static Equilibrium J. Dynamic Equilibrium 1. The ability to control equilibrium, either static or dynamic 2. The amount of friction between two objects that have not yet begun to move 3. A state of zero acceleration, where there is no change in the speed or direction of the body; may be static or dynamic 4. The force that results from the resistance of two surfaces rubbing against each other 5. The point at which all of the body’s mass and weight is equally balanced or equally distributed in all directions 6. The resistance to an object rolling across a surface (such as a ball rolling across a court) 7. State of equilibrium in which the body is at rest or completely motionless 8. The amount of friction between two objects that are sliding along each other

HSS 387 Basic Biomechanical Factors & Concepts: Self Study Worksheet Chapter 3 5 9. The resistance to a change in the body’s acceleration or the resistance to a disturbance of the body’s equilibrium 10. State of equilibrium in which all of the applied or inertial forces acting on the body are in balance; results in movement with unchanging speed or direction Assess the following scenarios and chose which will have better equilibrium, stability, and balance. Explain why. 1. A person standing on one foot or two? 2. A tall giraffe or a short bear, both on all four limbs? 3. A 200-lb football player or a 300-lb football player standing still? 4. A 6-ft man with very large feet or with very small feet? 5. A track star running erect or leaning forward? 6. A child running on an icy sidewalk or on a dry sidewalk? 7. A person standing erect in anticipation of an oncoming force, or a person leaning into the oncoming force? 8. A person sitting on a moving bicycle or a stationary bicycle? 9. Landing a vertical jump with your feet close together or shoulder-width apart? Describe each of Newton’s Laws of Motion in your own words and give a practical example of each. 1. Law of Inertia: 2. Law of Acceleration: 3. Law of Reaction:

HSS 387 Basic Biomechanical Factors & Concepts: Self Study Worksheet Chapter 3 6 For the following chart, assume that you possess the skill, strength, etc. to be able to perform each of the paired tasks. Decide which task would be easier to perform based on Newton’s Laws of Motion and explain why. Paired Task Explanation A Throw a baseball 60 mph or Throw a shot-put 60 mph B Kick a bowling ball 40 yards or Kick a soccer ball 40 yards C Bat a whiffle ball over a 320-yard fence or Bat a baseball over a 320-yard fence D Catch a shot-put that was thrown at 60 mph or Catch a softball that was thrown at 60 mph

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