EPChap10-Solution1

# EPChap10-Solution1 - 1 Chap. 10 HW1 Questions 1. Figure...

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1 1 Chap. 10 HW1 Questions 1. Figure 10-21b is a graph of the angular position of the rotating disk of Figure 10-21a. Is the angular velocity of the disk positive, negative, or zero at (a) t = 1 s, Slope of θ vs t is positive, therefore ω is positive. (b) t = 2 s, and Slope of vs t is zero, therefore ω is zero. (c) t = 3 s? Slope of vs t is negative, therefore ω is negative. (d) Is the angular acceleration positive or negative? Since ω is decreasing with time, angular acceleration α is negative. 2. Figure 10-22 is a graph of the angular velocity versus time for the rotating disk of Figure 10-21 a . For a point on the disk rim, rank the instants a , b , c , and d according to the magnitude of the (a) tangential and (b) radial acceleration, greatest first. a) Tangential acceleration dt d α = is the slope of an ω versus t curve. So the ranking is c, a, then b and d tie with zero tangential acceleration. b) Radial acceleration r r v a 2 2 / = = . So the ranking is b , then a and c tie, then d is last Problems 1. What is the angular speed of (a) the second hand of a smoothly running analog watch? Answer in radians per second. The second hand turns through 2 π radians (one full circle) during 60 s . T hus, 2 0.105 rad/s. 60 == (b) the minute hand of a smoothly running analog watch? Answer in radians per second.

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2 2 The minute hand turns through 2 π radians (one full circle) during 3600 s . Thus, ω == × 2 3600 175 10 3 π . r a d / s . (c) the hour hand of a smoothly running analog watch? Answer in radians per second.
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## This note was uploaded on 04/07/2008 for the course PHYS 213 taught by Professor Oshea during the Spring '08 term at Kansas State University.

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EPChap10-Solution1 - 1 Chap. 10 HW1 Questions 1. Figure...

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