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SECTION 10.3 • Angular and Linear Quantities 297 Rotational Motion About Fixed Axis Linear Motion & f " & i ) ( t v f " v i ) at ! f " ! i ) & i t ) ( t 2 x f " x i ) v i t ) at 2 & f 2 " & i 2 ) 2 ( ( ! f % ! i ) v f 2 " v i 2 ) 2a(x f % x i ) ! f " ! i ) ( & i ) & f )t x f " x i ) (v i ) v f )t 1 2 1 2 1 2 1 2 Kinematic Equations for Rotational and Linear Table 10.1 10.3 Angular and Linear Quantities In this section we derive some useful relationships between the angular speed and ac- every particle of the object moves in a circle whose center is the axis of rotation. Quick Quiz 10.4 Consider again the pairs of angular positions for the rigid object in Quick Quiz 10.1. If the object starts from rest at the initial angular position, Example 10.1 Rotating Wheel A wheel rotates with a constant angular acceleration of 2 . (A) If the angular speed of the wheel is 2.00 rad/s at t i " 0, through what angular displacement does the wheel rotate in Solution We can use Figure 10.2 to represent the wheel. We " (B) Through how many revolutions has the wheel turned during this time interval? Solution We multiply the angular displacement found in part (C) What is the angular speed of the wheel at t " 2.00 s? Solution Because the angular acceleration and the angular 1.75 rev $ ! " 630' # 1 rev 360' $ " 630' " (11.0 rad)(57.3'/rad) " 11.0 rad " (2.00 rad/s)(2.00 s) ) 1 2 (3.50 rad/s 2 )(2.00 s) 2 $ ! " ! f % ! i " & i t ) 1 2 (t
2 " We could also obtain this result using Equation 10.8 and the What If? Suppose a particle moves along a straight line with a constant acceleration of 3.50 m/s 2 . If the velocity of the particle is 2.00 m/s at t i $ 0, through what displacement does the particle move in 2.00 s? What is the velocity of the Answer Notice that these questions are translational and for the velocity, Note that there is no translational analog to part (B) because v f " v i ) at " 2.00 m/s ) (3.50 m/s 2 )(2.00 s) " 9.00 m/s " 11.0 m " (2.00 m/s)(2.00 s) ) 1 2 (3.50 m/s 2 )(2.00 s) 2 $ x " x f % x i " v i t ) 1 2 at
2 9.00 rad/s & f " & i ) ( t " 2.00 rad/s ) (3.50 rad/s 2 )(2.00 s) |