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Problems 101 14. A projectile is fired at an angle of 30° from the horizontal with some initial speed. Firing the projectile at what other 15. The maximum range of a projectile occurs when it is launched at an angle of 45.0° with the horizontal, if air 16. A projectile is launched on the Earth with some initial ve- locity. Another projectile is launched on the Moon with 2 .) 17. A coin on a table is given an initial horizontal velocity such that it ultimately leaves the end of the table and hits the 18. Explain whether or not the following particles have an acceleration: (a) a particle moving in a straight line with 19. Correct the following statement: “The racing car rounds the turn at a constant velocity of 90 miles per hour.” 20. At the end of a pendulum’s arc, its velocity is zero. Is its ac- celeration also zero at that point? 21. An object moves in a circular path with constant speed v. (a) Is the velocity of the object constant? (b) Is its accelera- 22. Describe how a driver can steer a car traveling at constant speed so that (a) the acceleration is zero or (b) the magni- 23. An ice skater is executing a figure eight, consisting of two equal, tangent circular paths. Throughout the first loop 24. Based on your observation and experience, draw a motion diagram showing the position, velocity, and acceleration 25. What is the fundamental difference between the unit vec- tors ˆr and ˆ" and the unit vectors i ˆ and ˆj ? 26. A sailor drops a wrench from the top of a sailboat’s mast while the boat is moving rapidly and steadily in a straight 27. A ball is thrown upward in the air by a passenger on a train that is moving with constant velocity. (a) Describe the path 28. A passenger on a train that is moving with constant velocity drops a spoon. What is the acceleration of the spoon rela- Section 4.1 The Position, Velocity, and Acceleration Vectors 1. A motorist drives south at 20.0 m/s for 3.00 min, then turns west and travels at 25.0 m/s for 2.00 min, and 2. A golf ball is hit off a tee at the edge of a cliff. Its x and y (a) Write a vector expression for the ball’s position as a and
y " (4.00 m/s)t # (4.90 m/s 2 )t 2 x " (18.0 m/s)t 1, 2 , 3 = straightforward, intermediate, challenging = full solution available in the Student Solutions Manual and Study Guide = coached solution with hints available at http://www.pse6.com = computer useful in solving problem = paired numerical and symbolic problems P R O B L E M S derivatives, obtain expressions for (b) the velocity vector v 3. When the Sun is directly overhead, a hawk dives toward the ground with a constant velocity of 5.00 m/s at 60.0° be- 4. The coordinates of an object moving in the xy plane vary |