You are designing a lathe motor, part of which consists of auniform cylinder who

Question

You are designing a lathe motor, part of which consists of auniform cylinder whose mass is 90 kg and whose radius is 0.40 mthat is mounted so that it turns w/o friction on its axis, which isfixed. The cylinder is driven by a belt that wraps around itsperimeter and exerts a constant torque. At t = 0, thecylinder's angular velocity is zero. At t = 25s, its angularmomentum is 500 rev/min. (a) What is the magnitude of thecylinder's angular momentum at t=25s? (b) At what rate is theangular momentum increasing? (c) What is the magnitude of thetorque acting on the cylinder? (d) What is the magnitude ofthe frictional force acting on a rim of the cylinder?

Explanation / Answer

moment of inertia = (1/2) m r2 = (1/2) * 90 * 0.402   =  7.2 . angular speed = 500 rev/min =  52.36 rad/s . (a)   angular momentum = moment ofinertia * angular speed = 7.2 * 52.36 = 377kg-m2/s . (b)   rate of angular momentum increase =   377 / 25 =    15.08 kg-m2 /s2 . (c)   magnitude of torque = rate ofangular momentum increase = 15.08 N-m . (d)    force = torque / r = 15.08 / 0.40 =    37.7 N . (c)   magnitude of torque = rate ofangular momentum increase = 15.08 N-m . (d)    force = torque / r = 15.08 / 0.40 =    37.7 N

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

---

---

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