Concept explainers
Problems 42 through 52 describe a situation. For each, draw a motion diagram, a force-identification diagram, and a free-body diagram.
42. An elevator, suspended by a single cable, has just left the tenth floor and is speeding up as it descends towards the ground floor.
43. A rocket is being launched straight up. Air resistance is not negligible.
44. A Styrofoam ball has just been shot straight up. Air resistance is not negligible.
45. You are a rock climber going upward at a steady pace on a vertical wall.
46. You’ve slammed on the brakes an your car is skidding to a stop while going down a 20° hill.
47. You’ve just kicked a rock on the sidewalk and it is now sliding along the concrete.
48. You’ve jumped down from a platform. Your feet are touching the ground and your kees are flexing as you stop.
49. You are bungee jumping from a high bridge. You are moving downward while the bungee cord is stretching.
50. Your friend went for a loop-the-loop ride at the amusement park. Her car is upside down at the top of the loop.
51. A spring-loaded gun shoots a plastic ball. The trigger has just been pulled and the bull is starting to move down the barrel. The barrel is horizontal.
52. A person on a bridge throws a rock straight down toward the water. The rock has just been released.
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