=-lim Figure 23 The people on this a PRACTICE PROBLEMS 45. You 41. A construction worker accidentally drops a brick phy from a high scaffold. stra a. What is the velocity of the brick after 4.0 s? a. W b. How far does the brick fall during this time? th 42. Suppose for the previous problem you choose your b. If coordinate system so that the opposite direction is y positive. C. If PRACTICE PROBLEMS a. What is the brick's velocity after 4.0 s? h b. How far does the brick fall during this time? 43. A student drops a ball from a window 3.5 m above 46. CH the sidewalk. How fast is it moving when it hits the ha sidewalk? the 44. A tennis ball is thrown straight up with an initial bo speed of 22.5 m/s. It is caught at the same distance the above the ground. 0.2 a. How high does the ball rise? a. b. How long does the ball remain in the air? Hint: The time it takes the ball to rise equals the time it takes to fall. b. 78 Chapter 3 . Accelerated Motion=-11 m 3 The people on this amusement-park ride experience free-fall accord Denve chang calcu used Do additional problems. Online Practice 45. You decide to flip a coin to determine whether to do you SE physics or English homework first. The coin is flipped 47. rick straight up. a. What are the velocity and acceleration of the coin at the top of its trajectory? e your b. If the coin reaches a high point of 0.25 m above where tion is you released it, what was its initial speed? c. If you catch it at the same height as you released it, how much time did it spend in the air? ? 46. CHALLENGE A basketball player is holding a ball in her above its the hands at a height of 1.5 m above the ground. She drops the ball, and it bounces several times. After the first bounce, the ball only returns to a height of 0.75 m. After ial the second bounce, the ball only returns to a height of istance 0.25 m. a. Suppose downward is the positive direction. What would the shape of a velocity-time graph look like for the first two bounces? s the b. What would be the shape of a position-time graph the first two bounces