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Solution: Section 12.6 Rotational DynamicsSection 12.7
Chapter 12, Problem 26E(choose chapter or problem)
Problem 26E
Section 12.6 Rotational Dynamics
Section 12.7 Rotation About a Fixed Axis
Starting from rest, a 12-cm-diameter compact disk takes 3.0 s to reach its operating angular velocity of 2000 rpm. Assume that the angular acceleration is constant. The disk’s moment of inertia is 2.5 × 10-5 kg m2.
a. How much torque is applied to the disk?
b. How many revolutions does it make before reaching full speed?
Questions & Answers
QUESTION:
Problem 26E
Section 12.6 Rotational Dynamics
Section 12.7 Rotation About a Fixed Axis
Starting from rest, a 12-cm-diameter compact disk takes 3.0 s to reach its operating angular velocity of 2000 rpm. Assume that the angular acceleration is constant. The disk’s moment of inertia is 2.5 × 10-5 kg m2.
a. How much torque is applied to the disk?
b. How many revolutions does it make before reaching full speed?
ANSWER:
Step 1 of 2
Part a
We are required to calculate the torque on the disk.
The disk is initially at rest
The final angular speed of the disk is rpm
rad/s
rad/s
The disk takes 3.0 s to reach the given angular speed.
Therefore, the angular acceleration is,
rad/s2
rad/s2
The given moment of inertia is kg
m2
Therefore, the torque is
N
m
N
m
N
m
Therefore, the required torque is N
m.