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**Unformatted text preview: **4/19/10 11:29 AM MasteringPhysics Page 1 of 38 http://session.masteringphysics.com/myct Manage this Assignment: Print Version with Answers Homework assignment 3 (covers Sections 3.1, 3.2, 3.3, 3.4, 3.5) Due: 2:00am on Monday, April 19, 2010 Note: You will receive no credit for late submissions. To learn more, read your instructor's Grading Policy First review Sections 3.1, 3.2, 3.3, 3.4, and 3.5 of Young and Freedman, including the worked examples. You should then be able to solve the problems given below. Note that you are allowed only 6 answer attempts per problem. Conceptual Problem about Projectile Motion Description: Conceptual questions about speed, peak characteristics, flight time, and range for an object undergoing projectile motion. Learning Goal: To understand projectile motion by considering horizontal constant velocity motion and vertical constant acceleration motion independently. Projectile motion refers to the motion of unpowered objects (called projectiles) such as balls or stones moving near the surface of the earth under the influence of the earth's gravity alone. In this analysis we assume that air resistance can be neglected. An object undergoing projectile motion near the surface of the earth obeys the following rules: 1. An object undergoing projectile motion travels horizontally at a constant rate. That is, the x component of its velocity, , is constant. 2. An object undergoing projectile motion moves vertically with a constant downward acceleration whose magnitude, denoted by , is equal to 9.80 near the surface of the earth. Hence, the y component of its velocity, , changes continuously. 3. An object undergoing projectile motion will undergo the horizontal and vertical motions described above from the instant it is launched until the instant it strikes the ground again. Even though the horizontal and vertical motions can be treated independently, they are related by the fact that they occur for exactly the same amount of time, namely the time the projectile is in the air. The figure shows the trajectory (i.e., the path) of a ball undergoing projectile motion over level ground. The time corresponds to the moment just after the ball is launched from position and . Its launch velocity, also called the initial velocity, is . Two other points along the trajectory are indicated in the figure. One is the moment the ball reaches the peak of its trajectory, at time with velocity . Its position at this moment is denoted by or since it is at its maximum height. The other point, at time with velocity , corresponds to the moment just before the ball strikes the ground on the way back down. At this time its position is , also known as ( since it is at its maximum horizontal range. ...

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