Chapter 19: Biomechanics Martin Caon Examination Questions and Answers in Basic Anatomy and Physiology Third Edition

Martin Caon Examination Questions and Answers in Basic Anatomy and Physiology Third Edition Chapter 19: Biomechanics 19.1 Force, Vectors and Levers 1. Choose the INCORRECT statement from the four below. a. Mass is the amount of matter contained in an object. b. Gravity is the name of the force that acts between any objects with mass. c. Weight is the pressure with which earth’s gravity acts on an object. d. For a standing person, base of support is the area bounded by their feet. Answer is C: Weight is a force while pressure is a force divided by the area upon which it is acting. 2. If a traction hanging mass is 3 kg, use Newton’s second law (or otherwise) to determine the gravitational force acting on the mass. a. 0.3 N b. 3 N c. 30 N d. 3 kg Answer is C: Newton’s second law: F = m × a; substituting in the numbers gives: F = 3 × 10 = 30 N (a = 9.8 ms−2 but 10 is close enough). 3. A person whose mass is 65 kg would have a weight closest to: a. 65 kg because mass and weight are directly proportional to each other (on earth) b. 650 kg because weight = mass × 10 (approximately) c. 65 N because F1 = −F2 (Newton’s third law) d. 650 N because F = m × a (Newton’s second law) Answer is D: Choice B is almost correct, but the unit of force is the newton while the kilogram is the unit of mass. 4. A person whose mass is 50 kg would have a weight closest to: a. 50 kg because mass and weight are directly proportional to each other (on earth) b. 50 N because F1 = −F2 (Newton’s third law) c. 500 kg because weight = mass × 10 (approximately) d. 500 N because F = m × a (Newton’s second law) Answer is D: Choice C is almost correct, but the unit of force is the newton while kilogram is the unit of mass. 5. In which of the following situations is an unbalanced force acting on a patient’s body? When the patient is: a. Lying stationary and supine on the bed b. Lying stationary and supine on the bed while the bed is being pushed a constant speed along a straight corridor c. Being assisted to sit still and upright on the edge of the bed d. Lying stationary and supine on the bed while the bed is being pushed around a corner in a corridor Answer is D: Changing the direction of motion by turning a corner (even if the speed does not change) requires an unbalanced force. Being still or moving at constant speed indicates that there are no unbalanced forces acting. 6. Which statement concerning friction is INCORRECT? a. Friction within liquids is greater than that between dry solids. b. Within the human body friction is reduced by fluids such as saliva, serous fluid, mucus. c. Friction exists whenever two surfaces are in contact. d. Sliding friction is less than static friction. Answer is A: Frictional forces within liquids are lower than within solids. Sliding friction is less than static friction. 7. Which one of the following statements is WRONG? a. A patient’s inertia may be decreased by using several people to assist in their transfer. b. The position of a person’s centre of gravity may be altered by altering the position of their arms and legs. c. Base of support may be increased by adopting a wide stance with your feet. d. Friction between a patient and the bed may be reduced by using a slide sheet. Answer is A: Inertia is a fixed attribute of an object that cannot be changed without changing its mass. 8. What is the weight of a nurse if her mass is 65 kg? (Use acceleration due to gravity of 10 m s−2) a. 65 kg b. 650 kg c. 65 N d. 650 N Answer is D: Weight is the force with which gravity attracts you to the earth. Use Newton’s second law: Weight, F = m × a = 70 × 10 = 700 N. The unit of force is the newton, N. 9. Choose the one correct statement. a. The unit of weight is the kilogram. b. The unit of mass is the newton. c. Weight is a force. d. Inertia is mass multiplied by 9.8. Answer is C: Weight is the force with which gravity attracts you to the earth. Your weight would be different on the moon (say), but your mass would be the same. 10. Which of the following is not an example of a force? a. Tension. b. Friction. c. Inertia. d. Weight. Answer is C: Inertia is not a force, it is a measure of mass. A measure of inertia of an object is the difficulty of setting the object in motion. 11. What does the term ‘friction’