18. Why is it important, when you are starting on a projectile motion problem, to first find the vertical and horizontal components of the velocity? 19. Augustine is an ecologist, and he is monitoring the plant life in a forest. He walks 89 meters west, 177 meters south, 443 meters east, 115 meters south, and then 70 meters north. What is his displacement vector from the starting point? 418 meters, 32.1 east of south 379 meters, 29.5 east of south 379 meters, 29.5 south of east 418 meters, 32.1 south of east 20. Which statement accurately describes the net force acting on the object depicted in the free body diagram above? (Imagine attached) The net force is to the south. The net force is to the north. The net force is to the east. The net force is to the west. 21. Kenneth is crossing a large river in a motor boat. With respect to the water, the boat is headed directly west with a speed of 6.3 m/s. The river he is crossing flows directly north with a speed of 3.1 m/s. To an observer on the shore, what is Kenneth's velocity vector? 7.0 m/s, 26.2 west of north 7.4 m/s, 31.9 west of north 7.4 m/s, 31.9 north of west 7.0 m/s, 26.2 north of west 22. Sven is going to try out for his high school's soccer team, so he is practicing his kicking skills. On one practice kick, he launches the soccer ball with a velocity of 17.9 meters per second, and at an angle of 21.6 above horizontal. What is the maximum height achieved by Sven's kick? 6.16 m 1.89 m 2.21 m 4.29 m 23. Two teams are each trying to pull a crate towards their side of the field. One team is pulling north with a force of 4491 N. The other team is pulling south with force of 4616 N. What is the net force on the crate? 9107 N south 9107 N north 125 N south 125 N north 24. Sven is going to try out for his high school's soccer team, so he is practicing his kicking skills. On one practice kick, he launches the soccer ball with a velocity of 17.9 meters per second, and at an angle of 21.6 above horizontal. Assuming the ball lands back on the field, what is the range of Sven's kick? 17.8 m 19.9 m 22.4 m 11.6 m 25. John walks 91.0 meters north, then turns and walks 166.2 meters east. What is the magnitude of John's displacement at the end of his walk? 189 m 129 m 16.0 m 168 m 26. Chloe is setting up a tennis ball launcher for a physics project. What angle should she set the launcher at to achieve the maximum possible range? 30 degrees 60 degrees 45 degrees 15 degrees 27. Allison kicks a soccer ball so that it has an initial velocity 19 meters per second, at an angle of 21 above the ground. How much time does it take for the soccer ball to reach its maximum height? 1.8 s 1.66 s 0.69 s .84 s 28. Which of the following objects has no net force acting upon it? an object that is changing direction. an object moving with constant velocity an object that is speeding up an object that is slowing down. 29. A farmer is marking his property line. He draws one line that is 769.0 meters long, and is 19.0 south of east. How long is the north-south component of the vector he has drawn? 250 m 727 m 267 m 769 m 30. Explain how you can identify if there is a net force acting on an object, both by looking at the object, and by looking at the free body diagram