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 2.25 kgm^2 about its central axis, is set spinning counterclockwise (which may be taken as the positive direction) at 227 rev/min. The second disk, with rotational inertia 8.44 kgm^2 about its central axis, is set spinning counterclockwise at 985 rev/min. They then couple together. What is their angular speed after coupling? If instead the second disk is set spinning clockwise at 985 rev/min. what are their angular velocity (rev/min). Quantitative Problems (SHOW YOUR WORK): I)o any 6 of remaining problems (9-20) for regular credit; Earn BONUS POINTS for each correct problem beyond regular credit. In the figure, block I of mass mi slides from rest along a frictionless ramp from height h = 3.3 m and then collides elastically with stationary block 2, which has mass m-2 = 5m_1. Compute the velocity v_2 of block 2 after the collision. After the collision, block 2 slides into a region where the coefficient of kinetic friction muk is 0 45 and comes to a stop in distance d within that region. Compute d.

Explanation / Answer

I am allowed to answer only 1 question at a time

A)
I1 = 2.25 kgm^2
w1i = 227 rev/min
I2 = 8.44 kgm^2
w2i = 985 rev/min

use conservation of angular momentum,
I1*w1i + I2*w2i = (I1+I2)*wf
2.25*227 + 8.44*985 = (2.25+8.44)*wf
wf = 825 rev/min
Answer:
825 rev/min
counterclockwise

B)
I1 = 2.25 kgm^2
w1i = 227 rev/min
I2 = 8.44 kgm^2
w2i = - 985 rev/min

use conservation of angular momentum,
I1*w1i + I2*w2i = (I1+I2)*wf
2.25*227 + 8.44*-985 = (2.25+8.44)*wf
2.25*227 - 8.44*985 = (2.25+8.44)*wf
wf = -730 rev/min
Answer:
-730 rev/min
clockwise

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

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