1. [-/2 Points] DETAILS SERCP11 8.1.OP.001. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER (a) A woman opens a 1.15 m wide door by pushing on it with a force of 38.5 N applied at the center of the door, at an angle perpendicular to the door's surface. What magnitude of torque (in N . m) is applied about an axis through the hinges? N . m (b) A second person opens the same door, using the same force, again directed perpendicular to the surface, but now the force is applied at the edge of the door. What magnitude of torque (in N . m) is applied about the axis through the hinges now? N . m Need Help? Read It 2. [-/4 Points] DETAILS SERCP11 8.1.OP.005. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER The figure below shows a horizontal rod, of length 4.4 m, with forces acting on it. A 30 N force acts at its left end, point O, in a direction down and to the left, 450 below horizontal. A 25 N force acts at its center, point C, in a direction up and to the right, 30 to the right of vertical. A 10 N force acts at the right end, in a direction down and to the right, 20 below horizontal. 25 N 1309 450 20 2.2 m 10 N 4.4 m 30 N (a) What is the net torque (in N . m) on the rod about an axis through O perpendicular to the page? magnitude N . m direction ---Select--- (b) What is the net torque (in N . m) on the rod about an axis through C perpendicular to the page? magnitude N . m direction ---Select--- Need Help? Read It3. [-/2 Points] DETAILS SERCP11 8.2.P.008. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Consider the following mass distribution where the x- and y-coordinates are given in meters: 5.0 kg at (0.0, 0.0) m, 3.2 kg at (0.0, 3.7) m, and 4.0 kg at (2.5, 0.0) m. Where should a fourth object of 6.9 kg be placed so that the center of gravity of the four-object arrangement will be at (0.0, 0.0) m? X= m y = 1m Need Help? Read It Watch It 4. [-/1 Points] DETAILS SERCP11 8.2.P.014. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER The Xanthar mothership locks onto an enemy cruiser with its tractor beam (see the figure below); each ship is at rest in deep space with no propulsion following a devastating battle. The mothership is at x = 0 when its tractor beams are first engaged, a distance d = 205 xiles from the cruiser. Determine the x-position in xiles (measured from x = 0) of the two spacecraft when the tractor beam has pulled them together. Model each spacecraft as a point particle with the mothership of mass M = 175 xons and the cruiser of mass m = 22.0 xons. HINT M m d x = xiles Need Help? Read It Watch It5. [-/1 Points] DETAILS SERCP11 8.3.P.035. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER The large quadriceps muscle in the upper leg terminates at its lower end in a tendon attached to the upper end of the tibia (see Figure a). The forces on the lower leg when the leg is extended are modeled as in Figure b, where T is the force of tension in the tendon, w is the force of gravity acting on the lower leg, and F is the force of gravity acting on the foot. Find T when the tendon is at an angle of 25.0 with the tibia, assuming that w = 28.0 N, F = 14.6 N, and the leg is extended at an angle 0 of 40.0 with the vertical. Assume that the center of gravity of the lower leg is at its center and that the tendon attaches to the lower leg at a point one-fifth of the way down the leg. (Give the magnitude.) Quadriceps Tendon Tibia a 25.0 T b N Need Help? Read It6. [-/1 Points] DETAILS SERCP11 8.3.P.019. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER A cook holds a 1.07-kg carton of milk at arm's length (see the figure below). What force F must be exerted by the biceps muscle? (Ignore the weight of the forearm. Give the magnitude.) IN Milk 75.00 25.0 cm F. 8.00 cm Need Help? Read It Submit Answer7. [-/3 Points] DETAILS SERCP11 8.4.OP.037. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER The figure below shows four objects at the corners of a rectangle, connected by rods of negligible mass. The center of the rectangle lies at the origin of an xy-coordinate system. The width of the rectangle (along the x-axis) is 4.00 m, and the height (along the y-axis) is 6.00 m. Starting at the top left and going clockwise, the masses of the objects are m, = 3.30 kg, my = 2.30 kg, me = 3.90 kg, and m = 1.70 kg. m 6.00 m O m 4.00 m- m 3 (a) What is the moment of inertia (in kg . m ) of the system about the x-axis? kg . m2 (b) What is the moment of inertia (in kg . m ) of the system about the y-axis? kg . m2 (c) What is the moment of inertia (in kg . m ) of the system about an axis through O and perpendicular to the page (that is, the z-axis)? kg . m2 Need Help? Read It 8. [-/3 Points] DETAILS SERCP11 8.4.P.043. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER A model airplane with a mass of 0.753 kg is tethered by a wire so that it flies in a circle 29.0 m in radius. The airplane engine provides a net thrust of 0.802 N perpendicular to the tethering wire. (a) Find the torque the net thrust produces about the center of the circle. N . m (b) Find the angular acceleration of the airplane when it is in level flight. rad/s (c) Find the linear acceleration of the airplane tangent to its flight path. m / s