Questions: 1) Calculate the moment of inertia (units of kg-m?) about an axis for a rotating body segment with total mass 10 kg, moment of inertia about its COG of 2 kg.m? and a COG located 0.4 m away from the axis of rotation.2] which advice from a tennis coach is wrong? a] Move the center of mass of the racket closer to your grip to better control the swing b] Flex the knee while running to rotate the leg faster while running c} Move the center of mass towards your grip to increase the angular momentum during the swing d] None of the above 3] When two forces are equal in magnitude, act on opposite sides of an axisr act in opposite linear directions, and have the same moment arms, they produce a] Pure force bl Pure torque c} Zero angular acceleration d1 Non-zero linear acceleration 4] Calculate the effective radius of gyration [units of meters) of the point mass system below about point A. m2 m1 n- Radius (m) 4.7 m3 51A 1.5 rn long barbell [4.5 kg} has two plates on it. A 146 kg plate is located 0.4 m from the left end and a 25 kg plate is located 0.15 m from the right end. Where is the center of gravity {[06} of this barbell system located {in meters} with respect to the right end? W3 = 4.5 kg W2=146 kg W1=25k9 6] During single leg support. all the ground reaction forces acting on the stance foot are concentrated at the . a] Center of gravity b] Radius of gyration c] Center of pressure d] Sacrum ir'] which statement is FALSE regarding the location of the center of pressure {CUP}? 3] The COP must lie within the base of support b] The COP must lie within the contact area ofthe foot during single leg support 1:} During standing. balance is maintained by locating the COP directly under the 06 on average d] During standing. the moment arm of the gravitational force is on average twice the COP distance from the same reference axis 8) Three forces of equal magnitude are applied to a body segment as shown in the picture below. Which force produces the least torque magnitude? (Hint: Draw moment arms to answer question) Axis - 9) Increasing the angle of lean (leaning forward) the magnitude of the torque produced by body weight about the ankle and causes the COP to move under the feet. a) Increases / Backward b) Produces no change in / Forward c) Increases / Forward d) Decreases / Forward 10) What movements will increase mediolateral standing stability from the neutral position? a) Folding arms around chest b) Widening stance c) Bending knees d) Standing heel to toe e) B and C 11-15 You will now answer a series of questions that work through the steps of a complete inverse dynamics problem to solve for the joint forces and torques at the ankle. In Q11 you will determine acceleration quantities from measured motion capture position signals. In Q12, you will compute the moment of inertia of the foot about the ankle base on an anthropometry table. In Q13 and Q14, you will use a free body diagram of the foot to calculate the unknown joint forces and torques. In Q15, you will apply your answer to calculating joint kinetics at the shank.11) What is the correct vertical velocity and vertical acceleration signals given the vertical position time trace of the foot below? Position (m) X Marker 0 0.2 0.4 0.6 0.8 Time (s) A C 20 20 Vx (m/s) Vx (m/s) 20 -20 0.2 0.4 0.6 0.8 0.2 0.4 0.6 0.8 200 200 Ax (m/s?) Ax (m/s?) 0 -200 .200 0.2 0.4 0.6 0.8 0 0.2 0.4 0.6 0.8 Time (s) Time (s) B D 20 20 Vx (m/s) Vx (m/s) -20 -20 0 0.2 0.4 0.6 0.8 0.2 0.4 0.6 0.8 200 200 Ax (m/s?) Ax (m/s?) 0 0 -200 -200 0 0.2 0.4 0.6 0.8 0.2 0.4 0.6 0.8 Time (s) Time (s)12) What is the moment of inertia {units of leg-ml] of the foot about the ankle? Round your answer to the nearest 1(100'\". Parameters of the Foot Relative Value Absolute Value Radius of gyration, rw 5.30 % of body height Distance from ankle to COG. d 4.70 % of body height Foot mass, mm 2.55 \"ii: of body mass Body Height Body Mass 13:: Assume the mass of the foot is 1.93 kg. Also assume the vertical acceleration of the foot is 13'0 misz. What is the vertical joint iorte {units of Ni acting on the foot at the ankle? Use the F30 on the next page. 14} Now also assume the mass of the foot is 1.93 kg and the moment of inertia of the foot about the ankle is 0.04 kg-mz. Also assume the angular acceleration of the foot is 110 radfsz. What is the joint torque [units of him] acting on the foot aboutthe ankle? Use the FBD below. 15:- Assume the answer to 014 is 90 him What is the joint torque {units 01 N-mi on the distal end of the shank? y