Two disks are mounted (like a merry-go-round) on low-friction bearings on the sa

Question

Two disks are mounted (like a merry-go-round) on low-friction bearings on the same axle and can be brought together so that they couple and rotate as one unit. The first disk, with rotational inertia 3.42 kg·m2 about its central axis, is set spinning counterclockwise (which may be taken as the positive direction) at 491 rev/min. The second disk, with rotational inertia 6.76 kg·m2 about its central axis, is set spinning counterclockwise at 989 rev/min. They then couple together. (a) What is their angular speed (rev/min) after coupling? (b) If instead the second disk is set spinning clockwise at 989 rev/min, what is their angular velocity (in rev/min, using the correct sign for direction) after they couple together?

Explanation / Answer

counterclockwise direction is the positive direction

angular velocity of first disc = 491 rev/min

first disc angular momentum =I11 = 1679.22

2 = 989 rev/min

second disc agular momentum = I22 =6685.64

a)

after coupling

(3.42+6.76)=1679.22+6685.64

= + 821.7 rev/min

b)

(3.42+6.76)=1679.22 - 6685.64

= - 379.85 rev/min

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.