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6 2 2 $x 2 80 m s REFLECT The negative sign associated with the acceleration implies the car is slowing down. 4 s to come to a stop. 1 m/s2. Because we know the initial speed, final speed, and the acceleration, we can calculate the distance over which the whale travels by rearranging v 2  v 20  2a $x . 1 2 < s  20 m REFLECT This is a little longer than the average size of an adult male sperm whale (about 16 m). 25 m/s. 43 m/s. 2 m). Assuming her acceleration is constant, we can calculate the acceleration by rearranging v 2  v 20  2a $x .

Mary wants Bill to catch the apple, which means Bill and the apple need to be at the same location at the same time. 75 m (presumably, Bill’s height). Assume the apple has an initial velocity of zero. We can compare this to the time it takes Bill to walk 120 m in order to determine how long Mary should wait to drop the apple. Once we know how long Mary waits, we can find the distance Bill is from Mary since he is walking at a constant speed of 2 m/s. Bill’s horizontal distance from Mary and the height Mary is in the air are two legs of a right triangle; the angle theta is related to these legs by the tangent.

The ball’s path consists of two legs: #1) traveling from its initial position to its maximum height and back to its initial position and #2) traveling from its initial position to the bottom of the cliff. The time and distance the ball travels during leg #1 are twice what it takes to travel from the initial position to the maximum height. At the maximum height, the ball’s speed is zero. The time and distance associated with leg #2 can be calculated knowing the ball’s initial velocity Chapter 2 Linear Motion 61 is 20 m/s straight down and it travels 30 m straight down.