I Y cobra.parkland.edu 828 PHY121_HWs - PHY-121-401H_2022SP PHY121_ICPs - PHY-121-401H_2022SP + 63 of 89 - + Automatic Zoom [ >> HW14 PHY121 3) A 221. kg, 5.48 m long see-saw has a 49.8 kg boy sitting on the left seat, and a 21.8 kg girl sits on the other; however, their 58.6 kg mom sits at the one place that will perfectly balance the see-saw. When the see-saw (Izz = 1/12 m L") is horizontal, what is: (Note: let "x" = right, and "y" = up) Answers: a) the force vector from the axle on the see-saw? [N], [N] ( 0.00 , +3.45x103 ) b) the torque from the boy on the see-saw? [N-m] +1.34x103 or 1.34x103 CCW c) the torque from the girl on the see-saw? [N-m] -586 or 586. CW d) the torque from the mom on the see-saw? [N-m] -753 It's balanced! e) the vector pointing from the axle to the place where ( +1.31 , 0.00 ) the mom sits? [m], [m] I Y cobra.parkland.edu C 828 PHY121_HWs - PHY-121-401H_2022SP PHY121_ICPs - PHY-121-401H_2022SP + 62 of 89 - + Automatic Zoom [ >> HW14 PHY121 2) A 135. kg, 4.92 m long see-saw (Izz = 1/12 m L2) has a girl on the left seat, a boy on the other seat, and their mom sitting on the see-saw 0.901 m to the left of the axle. The see-saw holds the girl up with 168. N, the boy with 438. N, and the mom with 579. N. When the see-saw is horizontal, what is: (Note: let "x" = right, and "y" = up) Answers: a) the moment of inertia of the see-saw? [kg-m?] 272 . b) the torque from the girl on the see-saw? [N-m] +413 or 413. CCW c) the torque from the boy on the see-saw? [N-m] -1.08x103 or 1.08x103 CW d) the torque from the mom on the see-saw? [N-m] +522. or 522. CCW e) the angular acceleration of the see-saw? [rad/s?] -0.523 or 0.523 CW I Y cobra.parkland.edu 828 PHY121_HWs - PHY-121-401H_2022SP PHY121_ICPs - PHY-121-401H_2022SP + 64 of 89 - + Automatic Zoom [ >> HW14 PHY121 4) A box (width = 5.25 m, height = 8.14 m, mass = 20.4 kg ) is pushed to the left by a 291. N horizontal force, located on the box's right-hand side, 3.41 m up from the floor. If the box starts to tip over its lower left corner (Izz = 224. kg-m? ), what is: (Note: let "x" = right, and "y" = up) Answers: a) the number of forces acting on the box? Four b) the torque from the push on the box? [N-m] +992. or 992. CCW c) the torque from gravity on the box? [N-m] -525 or 525. CW d) the net torque from all the forces acting on the box? [N-m] 1+467. or 467. CCW e) the box's angular acceleration? [rad/s?] +2.08 or 2.08 CCW