ch6 problem50

Physics: Principles with Applications

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Chapter 6, Problem 50 Question Problem (a) The baseball was at rest at the top of the tree. Therefore, the total mechanical energy of the ball is equal to its gravitational potential energy. That is, where is the mass of the baseball, is the acceleration due to gravity, and is the vertical displacement. Let be the speed of the ball when it hits the ground. The total mechanical energy of the ball at a point just above the ground is equal to the kinetic energy of the ball. That is, . Apply the principle of conservation of mechanical energy. Solve for . Substitute for , and 13.0 m for . Thus, the baseball would hit the ground with a speed of . (b) Express the mass of the baseball in kilograms. Find the total mechanical energy of the ball before it was dropped from the tree. Find the total mechanical energy
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Unformatted text preview: of the ball at a point just above the ground. http://www.hwproblems.com/cgi-bin/book.cgi?bookid=0044&cptn=6pr50&id=489216 (1 of 2) [2/4/2008 4:37:49 PM] http://www.hwproblems.com/cgi-bin/book.cgi?bookid=0044&cptn=6pr50&id=489216 The decrease in the mechanical energy corresponds to the work done by the force of air resistance on the ball. The net work done due to the air resistance can be calculated as shown below. Let be the average force of air resistance, and let be the distance over which the force acts. Consider the equation connecting the net work done and the average force of air resistance. Substitute for , 13.0 m for , and solve for . Thus, the average force of air resistance on the ball would be . http://www.hwproblems.com/cgi-bin/book.cgi?bookid=0044&cptn=6pr50&id=489216 (2 of 2) [2/4/2008 4:37:49 PM]...
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ch6 problem50 - of the ball at a point just above the...

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