This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: sanchez (ds28677) oldmidterm 03 Turner (58220) 1 This printout should have 24 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A rotating bicycle wheel has an angular speed of 56 / s at 4 . 6 s and a constant angular acceleration of 21 / s 2 . With the center of the wheel at the origin, the valve stem is on the positive xaxis (horizontal) at t = 1 . 4 s. Through what angle has the valve stem turned between 1 . 4 s and 8 . 5 s? Correct answer: 449 . 785 . Explanation: Let : 1 = 56 / s , t 1 = 4 . 6 s , = 21 / s 2 , = 0 , t = 1 . 4 s , and t = 8 . 5 s . The initial angular velocity can be deter mined from 1 = + ( t 1 t ) = 1 ( t 1 t ) = 56 / s (21 / s 2 ) (4 . 6 s 1 . 4 s) = 11 . 2 / s . This 2 = ( t 2 t ) + 1 2 ( t 2 t ) 2 = ( 11 . 2 / s) (8 . 5 s 1 . 4 s) + 1 2 (21 / s 2 ) (8 . 5 s 1 . 4 s) 2 = 449 . 785 . 002 (part 1 of 3) 10.0 points A beetle takes a joy ride on a pendulum. The string supporting the mass of the pendulum is 190 cm long. If the beetle rides through a swing of 49 , how far has he traveled along the path of the pendulum? Correct answer: 162 . 49 cm. Explanation: Let : r = 190 cm , and = 49 . Arc length is defined as s = r = (190 cm)(49 ) parenleftBig 180 parenrightBig = 162 . 49 cm . 003 (part 2 of 3) 10.0 points What is the displacement experienced by the beetle while moving theough the same angle 49 ? Correct answer: 157 . 583 cm. Explanation: Using the law of cosines, we have bardbl vector R bardbl = radicalbig r 2 + r 2 2 r r cos = r radicalbig 2 (1 cos ) = (190 cm) radicalbig 2(1 cos 49 ) = 157 . 583 cm . Alternative Solution: Divide the isosce les triangle in half. Then bardbl vector R bardbl = 2 . r sin parenleftbigg 2 parenrightbigg = 2 . 0 (190 cm) sin24 . 5 = 157 . 583 cm . 004 (part 3 of 3) 10.0 points If the pendulum at some instant is swinging at 1 . 7 rad / s, how fast is the beetle traveling? Correct answer: 323 cm / s. Explanation: sanchez (ds28677) oldmidterm 03 Turner (58220) 2 Let : = 1 . 7 rad / s . Linear and angular velocity are related by v = r = (190 cm)(1 . 7 rad / s) = 323 cm / s . keywords: 005 10.0 points At t = 0, a wheel rotating about a fixed axis at a constant angular deceleration of 0 . 66 rad / s 2 has an angular velocity of 2 . 7 rad / s and an angular position of 6 . 5 rad. What is the angular position of the wheel after 3 s? Correct answer: 11 . 63 rad. Explanation: Let : = . 66 rad / s 2 , = 2 . 7 rad / s , = 6 . 5 rad , and t = 3 s ....
View Full
Document
 Spring '08
 Turner
 Physics

Click to edit the document details