Multiple Choice – 5 Questions x 2pts = Please write your answers in the space provided. # correct score 1. A massless string exerts a horizontal force of 60 Newtons on a 4-kg box. This causes the box to slide across a level floor and speed up with an acceleration of 3 m/s 2 . The friction force acting on the box (in Newtons) is: A. 0 B. 12 C. 15 D. 48 E. 72 2. Greg drops off a bridge with a bungee cord attached to his feet. Which of the following best describes the net force acting on Greg during the time that his motion is being slowed by the bungee cord? A. constant magnitude and directed downward B. decreasing magnitude and directed upward C. increasing magnitude and directed upward D. decreasing magnitude and directed downward E. increasing magnitude and directed downward 3. A block slides down an incline at constant speed. Which of the following statements is true of the block-earth system? A. The kinetic energy is conserved and the mechanical energy is conserved.
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