Angular Kinetics Worksheet 1. What is the net torque generated during this biceps curl? Assume the forearm is horizontal. Which way would the arm move? Biceps F 400 N Forearm m 3 kg W = 20 N 0.01 m 0.1 m 0.3 m 2. Calculate the effective torque at the shoulder if the mass of the upper arm is 0.7kg and the mass of the forearm and hand is 1.2 kg: 8cm 18cm 8 1 3. Calculate the torque: (i) 4m 4. Calculate the torque: (ii) 7m 60 N 30 N 5. Calculate the torque: (iii) 60 N 3m 70 6. Calculate the force required for static equilibrium: 50N 3m 2m 7. Calculate the force required for static equilibrium: (ii) F (muscle) com 4 kg 8 N (weight) 0.85 m 0.35 m 2 cm Joint 2 8. Two children sit on opposite sides of a playground seesaw. Pete, who weights 220N, sits 1.5m from the axis of the seesaw, and Eric, who weights 200N, sits 1.7m from the axis of the seesaw. How much torque is created at the axis by each child? In which direction will the seesaw tip? 9. Tom's leg angularly accelerates 3000/s around the hip joint during a roundhouse kick in the transverse plane. The moment of inertia of the leg around the axis of rotation for this kick is 0.75kg*m. How large is the torque that produces this acceleration? 10. What is the torque generated at the elbow by a 90N force pulling on the forearm at an angle of 110 from the horizontal at a point 18cm from the elbow's axis of rotation? The forearm is positioned horizontal to the ground. What acceleration will this torque produce if the moment of inertia of the forearm is 0.45 kg*m? 90 N 18cm 110 3 11. Sara is standing on the ground with the right hip flexed 90 and the right knee flexed 55, with the right ankle plantar flexed 90 such that it is in a straight line with the shank. If she wants to extend her knee with an angular acceleration of 200/s, find the force she will need to exert with the quadriceps muscle group to do so. Assume that the quadriceps muscles and the weight of the leg are the only forces to be accounted for in this scenario. Mass of shank and foot=4.15kg Length of shank and foot=0.55m Knee is flexed 55 distance between line of pull of the quadriceps and knee joint center = 5.3cm Shank/Foot COM is in center of combined segments Shank/Foot Moment of Inertia (I)= 0.217 kg*m2 4 Angular Kinetics Worksheet Answers 1.-4.94 Nm, elbow would extend 2. -2.67 Nm 3. -240 Nm 4. 210 Nm 5. -169.14 Nm 6. -75 N in y-direction 7. 1026.5 N in y-direction 8. Pete=330Nm; Eric= 340Nm; seesaw will tip towards Eric 9. 39.27 Nm 10. 15.22 Nm; 33.82 rad/s 11. 135.64 N 5