17. You are doing a front kick. At a given instant, your leg (mass of 10 kg L= 1.1 m) is straight and horizontal, as shown below. What is the magnitude of the torque about the hip joint on your leg due to gravity at this instant? (Assume your leg is uniform) A. 54 Nm B. 98 Nm C. 108 Nm D. 11 Nm E. ONm 18. What spring constant k would you need to have a 3 kg mass oscillate on the spring with the same period T as the mass would have hanging from a simple pendulum of length 0.5 meters? A. 13 N/m B. 59 N/m C. 0.15 N/m D. 6 N/m E. 177 N/m 19. You observe a 10 kg object moving to the left with a constant velocity of 5 m's for two seconds. The net force acting on the object during this time must have been: A. 50 N B. ON C. 25 N D. -50 N E. -25 N Page 720. A roller coaster of mass 420 kg is moving with a speed of 10.0 m's at position A as shown The vertical height at position A above ground level is 200 m and at position C is 160 m Assume friction is negligible. The speed of the roller coaster at point C is approximately 200 m 160 m - - Potential Energy = 0 A. 56 m's B. 30 m's C. 63 m's D. 59 m's E. 28 m's 21. A student is in possession of three tunuing forks each labeled with their respective frequencies (354 Hz, 365, and 382 Hz). If all three tuning forks are struck at the same instant the student will be able to hear the following number of beats per second: A. 17 B. 11, 17, and 28 C. 747 and 736 D. 11 E. 719 and 736 22. An inelastic collision between two objects is characterized by the following A. Total energy of the system is conserved B. Total kinetic energy of the system remains constant C. Total momentum of the system is conserved D. Both A and B are true E. Both A and C are true Page 823. A person was pushing a box up an incline (as shown below). As the person pushes, which of the free body diagrams provided best describes the forces acting on the box? A. B. FN FN Fpush Fpush fx W W C. D. FN FN Fpush Fpush X fx W W Page 924. A 2-kg chunk of putty moving at 3 m's collides with and sticks to a 8-kg bowling ball initially at rest on a frictionless surface. The bowling ball and putty (stuck to the ball) then move with a momentum of A 0.75 Ns B. 24 kgm's C. 6 kgm's D. 12 Ns E. 48 kgm's 25. The position versus time graph below represents the motion of an object moving in a straight line. 12 A position (centimeters) o 2 4 6 8 10 12 14 16 time (seconds) What is the object's instantaneous velocity at f = 2.0 s? A. 0 cm's B. 3.5 cm/'s C. 2.5 em's D. 1.5 em's E. 6.5 cm's