1 / 12

PHYS 131 student:

PHYS 131 student:. Announcements. Homework for tomorrow… (Ch. 11, Probs 10, 20, & 23) 10.76: 120 J Office hours… M 3-4 pm TWR 9-10 am F 1-2 pm Tutorial Learning Center – Houston Hall 113 MWR 8 am-6 pm T 8 am-7 pm F 8 am-5 pm.

lynde
Download Presentation

PHYS 131 student:

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. PHYS 131 student:

  2. Announcements • Homework for tomorrow… (Ch. 11, Probs 10, 20, & 23) 10.76: 120 J • Office hours… M 3-4 pm TWR 9-10 am F 1-2 pm • Tutorial Learning Center – Houston Hall 113 MWR 8 am-6 pm T 8 am-7 pm F 8 am-5 pm

  3. Chapter 11 Rotation (Relating Translational and Rotational Variables)

  4. Last time… • Rotational Position Rotating Body: • Rotational Displacement: • Rotational Velocity: • Rotational Acceleration: Kinematic Equations for Rotational Motion: s r 

  5. Demo Question The wheel rolls thru  = 2 … • How far did the center move?

  6. Quiz Question 1 A wheel initially has an angular velocity of 18 rad/s but is slowing down at a rate of 2.0 rad/s2. By the time it stops it will have turned through: • 13 rev • 26 rev • 39 rev • 52 rev • 81 rev

  7. Example The tub of a washer goes into its spin-dry cycle, starting from rest and reaching an angular speed of 5.0 rev/s in 8.0 s. At this point, the person doing the laundry opens the lid, and a safety switch turns off the washer. The tub slows to rest in 12.0 s. Through how many revolutions does the tub turn during the entire 20 s interval? Assume constant rotational acceleration while it is starting and stopping.

  8. Section 11.4: Relating Translational and Rotational Variables Can we relate angular & translational velocity? Yes! • Arc length is • Taking the time derivative • The translational speed, v, of a point on a rotating object equals the distance of that point from the axis of rotation, r, multiplied by the angular speed,  v v s  r

  9. Relationship between Translational and Rotational Acceleration Likewise… The tangential acceleration, at, of a point on a rotating object equals the distance of that point from the axis of rotation, r, multiplied by the angular acceleration, 

  10. Relations between translational and rotational quantities Summarizing…

  11. Quiz Question 2 A child riding on a playground merry-go-round rotates at a rate of 1.0 rad/s in a circle of radius 3.0 m. The translational speed of the child is: • 3.0 m/s • 0.33 m/s • 19 m/s • 0.48 m/s • 9.4 m/s

  12. Quiz Question 3 A ladybug sits at the outer edge of a record rotating at a constant 45 r.p.m. A gentleman bug sits halfway between her and the axis of rotation. Which of the following is/are true? • The ladybug’s linear speed is the same as the gentleman bug’s • The ladybug and the gentleman bug will have the same angular displacement after 1.0 s. • The ladybug and the gentleman bug have the same tangential acceleration. • I only • I & II • II &III • I, II, & III • None of these

More Related