Figures Chapter 2 College Physics, 6th Edition Wilson / Buffa / Lou © 2007 Pearson Prentice Hall This work is protected by United States copyright laws and is provided solely for the use of instructors in teaching their courses and assessing student learning. Dissemination or sale of any part of this work (including on the World Wide Web) will destroy the integrity of the work and is not permitted. The work and materials from it should never be made available to students except by instructors using the accompanying text in their classes. All recipients of this work are expected to abide by these restrictions and to honor the intended pedagogical purposes and the needs of other instructors who rely on these materials. Figure 2-1 Distance – total path length Figure 2-4 Distance (scalar) and displacement (vector) Learn by Drawing 2-1 Cartesian Coordinates and OneDimensional Displacement Figure 2-6 Uniform linear motion – constant velocity Figure 2-7 Position-versus-time graph for an object in uniform motion in the negative x-direction Figure 2-8 Position-versus-time graph for an object in nonuniform linear motion Figure 2-9 Acceleration – the time rate of change of velocity Learn by Drawing 2-2 Signs of Velocity and Acceleration Figure 2-10 Velocity-versus-time graphs for motions with constant accelerations Figure 2-11 Away they go! Figure 2-12 Vehicle stopping distance Figure 2-13 v-versus-t graphs, one more time Figure 2-14 Free fall and air resistance Figure 2-16 Free fall up and down (b) Figure 2-17 Speed versus velocity 21. An insect crawls along the edge of a rectangular swimming pool of length 27 m and width 21 m ( Fig. 2.17). If it crawls from corner A to corner B in 30 min, (a) what is its average speed, and (b) what is the magnitude of its average velocity? (a) 2.7 cm/s (b) 1.9 cm/s Figure 2-18 Position versus time 24. A plot of position versus time is shown in Fig. 2.18 for an object in linear motion. (a) What are the average velocities for the segments AB, BC, CD, DE, EF, FG, and BG? (b) State whether the motion is uniform or nonuniform in each case. (c) What is the instantaneous velocity at point D? Figure 2-19 Position versus time 25 In demonstrating a dance step, a person moves in one dimension, as shown in Fig. 2.19. What are (a) the average speed and (b) the average velocity for each phase of the motion? (c) What are the instantaneous velocities at t 1.0 s, 2.5 s, 4.5 s, and 6.0 s? (d) What is the average velocity for the interval between t 4.5s and t 9.0s? [Hint: Recall that the overall displacement is the displacement between the starting point and the ending point.] Figure 2-20 When and where do they meet? 30. Two runners approaching each other on a straight track have constant speeds of and respectively, when they are 100 m apart (Fig. 2.20). How long will it take for the runners to meet, and at what position will they meet if they maintain these speeds? 12.5 s, 56.3 m (relative to runner on left) Figure 2-21 Description of motion 38. Describe the motions of the two objects that have the velocity-versus-time plots shown in Fig. 2.21. Figure 2-22 Velocity versus time 50. What is the acceleration for each graph segment in Fig. 2.22? Describe the motion of the object over the total time interval. Figure 2-23 Velocity versus time 51. Figure 2.23 shows a plot of velocity versus time for an object in linear motion. (a) Compute the acceleration for each phase of motion. (b) Describe how the object moves during the last time segment. Figure 2-24 Hit the professor 104. In Fig. 2.24, a student at a window on the second floor of a dorm sees his math professor walking on the sidewalk beside the building. He drops a water balloon from 18.0 m above the ground when the professor is 1.00 m from the point directly beneath the window. If the professor is 170 cm tall and walks at a rate of does the balloon hit her? If not, how close does it come? hits 14 cm in front of the professor Figure 2-25 From where did it come? 107 It takes 0.210 s for a dropped object to pass a window that is 1.35 m tall. From what height above the top of the window was the object released? (See Fig. 2.25.) 1.49 m above the top of the window Figure 2-26 A tie race 111 A car and a motorcycle start from rest at the same time on a straight track, but the motorcycle is 25.0 m behind the car ( Fig. 2.26). The car accelerates at a uniform rate of 3.70 m/s2 and the motorcycle at a uniform rate of (a) How much time elapses before the motorcycle overtakes the car? (b) How far will each have traveled during that time? (c) How far ahead of the car will the motorcycle be 2.00 s later? (Both vehicles are still accelerating.) (a) 8.45 s (b) (c) 13 m Figure 2-28 Down she comes 117 Let’s investigate a possible vertical landing on Mars that includes two segments: free fall followed by a parachute deployment. Assume the probe is close to the surface, so the Martian acceleration due to gravity is constant at Suppose the lander is initially moving vertically downward at at a height of above the surface. Neglect air resistance during the free-fall phase. Assume it first free-falls for (The parachutes don’t open until it is from the surface. See Fig. 2.28.) (a) Determine the lander’s speed at the end of the 8000-m freefall drop. (b) At above the surface, the parachute deploys and the lander immediately begins to slow. If it can survive hitting the surface at up to determine the minimum constant deceleration needed during this phase. (c) What is the total time taken to land from the original height of 20000 m? (a) -297 m/s (b) 3.66 m/s2 (c) 108 s