ism_chapter_09 - Chapter 9 Rotation Conceptual Problems*1...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
623 Chapter 9 Rotation Conceptual Problems *1 Determine the Concept Because r is greater for the point on the rim, it moves the greater distance. Both turn through the same angle. Because r is greater for the point on the rim, it has the greater speed. Both have the same angular velocity. Both have zero tangential acceleration. Both have zero angular acceleration. Because r is greater for the point on the rim, it has the greater centripetal acceleration. 2 ( a ) False. Angular velocity has the dimensions T 1 whereas linear velocity has dimensions T L . ( b ) True. The angular velocity of all points on the wheel is d θ / dt. ( c ) True. The angular acceleration of all points on the wheel is d ω / dt. 3 •• Picture the Problem The constant-acceleration equation that relates the given variables is θ α ω ω + = 2 2 0 2 . We can set up a proportion to determine the number of revolutions required to double ω and then subtract to find the number of additional revolutions to accelerate the disk to an angular speed of 2 ω . Using a constant-acceleration equation, relate the initial and final angular velocities to the angular acceleration: θ α ω ω + = 2 2 0 2 or, because 2 0 ω = 0, θ α ω = 2 2 Let θ 10 represent the number of revolutions required to reach an angular velocity ω : 10 2 2 θ α ω = (1) Let θ 2 ω represent the number of revolutions required to reach an angular velocity ω : ( ) ω θ α ω 2 2 2 2 = (2) Divide equation (2) by equation (1) and solve for θ 2 ω : ( ) 10 10 2 2 2 4 2 θ θ ω ω θ ω = =
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Chapter 9 624 The number of additional revolutions is: ( ) rev 30 rev 10 3 3 4 10 10 10 = = = θ θ θ and correct. is ) ( c *4 Determine the Concept Torque has the dimension 2 2 T ML . ( a ) Impulse has the dimension T ML . ( b ) Energy has the dimension 2 2 T ML . correct. is ) ( b ( c ) Momentum has the dimension T ML . 5 Determine the Concept The moment of inertia of an object is the product of a constant that is characteristic of the object’s distribution of matter, the mass of the object, and the square of the distance from the object’s center of mass to the axis about which the object is rotating. Because both ( b ) and ( c ) are correct correct. is ) ( d *6 Determine the Concept Yes. A net torque is required to change the rotational state of an object. In the absence of a net torque an object continues in whatever state of rotational motion it was at the instant the net torque became zero. 7 Determine the Concept No. A net torque is required to change the rotational state of an object. A net torque may decrease the angular speed of an object. All we can say for sure is that a net torque will change the angular speed of an object.
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern