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Unformatted text preview: CHAPTER 5 DYNAMICS OF UNIFORM CIRCULAR MOTION CONCEPTUAL QUESTIONS 3. REASONING AND SOLUTION The equations of kinematics (Equations 3.3 - 3.6) cannot be applied to uniform circular motion because an object in uniform circular motion does not have a constant acceleration. While the acceleration vector is constant in magnitude a v r = 2 / c h , its direction changes constantly -- it always points toward the center of the circle. As the object moves around the circle the direction of the acceleration must constantly change. Because of this changing direction, the condition of constant acceleration that is required by Equations 3.3 3.6 is violated. ______________________________________________________________________________________ ______ 4. REASONING AND SOLUTION Acceleration is the rate of change of velocity. In order to have an acceleration, the velocity vector must change either in magnitude or direction, or both. Therefore, if the velocity of the object is constant, the acceleration must be zero. On the other hand, if the speed of the object is constant, the object could be accelerating if the direction of the velocity is changing. ______________________________________________________________________________________ ______ 6. REASONING AND SOLUTION From Example 7, the maximum safe speed with which a car can round an unbanked horizontal curve of radius r is given by v gr s = . Since the acceleration due to gravity on the moon is roughly one sixth that on earth, the safe speed for the same curve on the moon would be less than that on earth. In other words, other things being equal, it would be more difficult to drive at high speed around an unbanked curve on the moon as compared to driving around the same curve on the earth....
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This note was uploaded on 12/28/2011 for the course PHY 2053 taught by Professor Darici during the Spring '09 term at FIU.
- Spring '09
- Circular Motion