-9.8 m/x Since v is steadily decreasing, the acceleration is constant and negative. s.com to access assigned homework and self-study tools such as actice quizzes, video solutions to problems, and a whole lot more! problems ENV Environmental problems CH Challenge problems Comp Computer problems chapter, you should be able to: , velocity, and 2.27, 2.28, 2.30, 2.31, 2.32. 2.33, 2.34; Problems 2.55, 2.56. 2.57, 2.58, 2.61, 2.62, 2.63, 2.64. 2.65, 2.66, 2.67, 2.68, 2.69, 2.5, 2.6; 2.70, 2.81, 2.87, 2.93 2.20, 2.21, 2.22, LO 2.4 Describe how gravity near Earth's surface provides an exam- ple of constant acceleration. ocity and For Thought and Discussion Question 2.7; Exercises 2.29. 2.35, 2.36, 2.37, 2.38, 2.39, 2.40; Problems 2.59. 2.60, 2.71. 2.4, 2.8, 2.9, 2.10; 2.72, 2.73, 2.74, 2.75, 2.76, 2.77, 2.78, 2.79, 2.80, 2.82, 2.84. lems 2.50, 2.83 2.85, 2.86, 2.89, 2.90, 2.91. 2.92, 2.07 leration is constant. LO 2.5 Use calculus to deal with nonconstant acceleration. Exercises 2.26, Problems 2.53, 2.54, 2.88, 2.045 2.95, 2.96 definitions equivalent? Give twelexamples to demonstrate your . . . . . . .. conclusion. stantancous velocity 5. Is it possible to be at position .x - 0 and still be moving? 6. Is it possible to have zero velocity and still be accelerating? ty? 7. If you know the initial velocity vo and the initial and final heights of a day's driving and 3b and y. you can use Equation 2.10 to solve for the time / when ould the difference be- the object will be at height y. But the equation is quadratic in f. so cement? you'll get two answers. Physically, why is this? age speed: (0) the av- 8. In which of the velocity-versus-time graphs shown In Fig. 2.14 speed over a time in- would the average velocity over the interval shown equal the uver- ge velocity. Are these age of the velocities at the ends of the interval? 4.9 m/'s. f is the time in seconds,the take tance 33. Calif toma Distance (m) system trains of son 5 6 brake Time (!) needed FIGURE 2.15 Exercise 18 km/h w 34. You're 19. A model rocket is launched straight upward. Its altitude road, a y as a function of time is given by y - br - ch . where the acce Page 2 / 3 WE S P REA F5 F6 F7 F8 Syou'll get two answers. Physically, why is this? 8. In which of the velocity-versus-time graphs shown In Fig. 2 would the average velocity over the interval shown equal the u age of the velocities at the ends of the interval? b - 82 m/s, c = 4.9 m/s'. / is the time in seconds, and y ters. (a) Use differentiation to find a general expression for the no et's velocity as a function of time. (b) When is the velocity zerg Section 2.3 Acceleration 20. You're driving at the 50 km/h speed limit when you spot a tian showing a speed-limit increase to 90 km/h. If it takes 25.3,10 reach the new speed limit, what's your average acceleration Express it in m/s. 21. Starting from rest, a subway train first accelerates to 25 m/, . brakes. Forty-eight seconds after starting. it's moving at 17 What's its average acceleration in this 48-s interval? 22. NASA's New Horizons spacecraft was launched in 2006 and past Pluto in 2015. New Horizons' solid-fuel booster rocket go it an average acceleration of 6.16 m/s. bringing it to a speed , 16.3 km/s before the booster dropped away. How long did they acceleration last? 23. An egg drops from a second-story window, taking 1.12 log.Answers to Chapter Questions 33 on to. at time a = do + bt, The collar transmits data on the tiger's position and velocity. Figure 2.16 shows the tiger's velocity as a function of time as it moves on a xpressions for one-dimensional path. s functions of . right wants a car to Ar. The field ight above the D eleased. Velocity, Time,/-- H before it hits G straight down floor). What -. left When would answers.) FIGURE 2.16 The tiger's velocity (Passage ur opinion on Problems 98-102.) is kept awake ow the faucet. 98. At which marked point(s) is the tiger not moving? trikes the sink a. Eonly . How many b. A. E, and H :? c. C and F belt in an au- d. none of the points (it's always moving) stance h above 99. At which marked point(s) is the tiger not accelerating? duct into each a. E only ives along the b. A. E, and H . expressed as c. C and F the instant the d. all of the points (it's never accelerating) 100. At which point does the tiger have the greatest speed? 2.7 over time. a. B b. C c. D d. F 101. At which point does the tiger's acceleration have the greatest lly with time: magnitude? tarts from rest, a. B b. C c. D d. F 102. At which point is the tiger farthest from its starting position at is given by 1 = 0? tants with ap- a. C b. E c. F d. H me 1 = 0, find = 0 and (b) its Answers to Chapter Questions lly with time: . . . . . . . . . . . . . . . . . .. .. . Assuming the Answer to Chapter Opening Question s a function of ) Will it travel Although the ball's velocity is zero at the top of its motion, its acceler- ation is -9.8 m/s', as it is throughout the toss. ground. At the Answers to GOT IT? Questions speed is greater for (c) 3 3 Q + mant speed; (a) reverses; (d) speeds up it at which they 2.4 (a) halfway between the times; because its acceleration is con