What is the Initial Angular Acceleration of a Disk Released from Rest?

In this case, D = 0.3m.In summary, the initial angular acceleration of the cylinder can be found by using the Parallel Axis theorem to calculate the moment of inertia, which is needed since the axis of rotation is not through the centre of mass. The moment of inertia can be found by adding the moment of inertia of a solid disk and the product of the mass and the distance from the centre of mass to the new axis. The result of this calculation will give the initial angular acceleration of the cylinder.
  • #1
klm
165
0
A 5.0 kg, 60-cm-diameter disk rotates on an axle passing through one edge. The axle is parallel to the floor. The cylinder is held with the center of mass at the same height as the axle, then released.

What is the cylinder's initial angular acceleration?

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ok so this is what i think i should do:

Torque= I [tex]\alpha[/tex]

and i need to find the F(weight)= mg = (5)(9.8) = 49 N
radius = .5(.6)= .3
Torque= Fd = 49(.3) = 14.7
14.7 = I [tex]\alpha[/tex]
this is the part which i am not sure on, does I = .5 m r^2 = .5(5)(.3^2) = .225
14.7 .225 [tex]\alpha[/tex]
[tex]\alpha[/tex] = 65.33
but this answer is incorrect, and i do not know where i am making the mistake.
 
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  • #2
please can someone help
 
  • #3
Try using the Parallel Axis theorem to find the moment of inertia. This is needed because the axis of rotation is not through the centre of mass of the disk.

[tex]I = I_{CM} + MD^2[/tex]

where [tex]I_{CM}[/tex] is the moment of inertia for a solid disk, M is the mass of the disk and D is the distance from the centre of mass to the new axis.
 

FAQ: What is the Initial Angular Acceleration of a Disk Released from Rest?

What is angular acceleration?

Angular acceleration is the rate of change of angular velocity. It measures how quickly the rotational speed of an object changes over time.

How is angular acceleration different from linear acceleration?

Angular acceleration is a measure of how fast an object's rotation is changing, while linear acceleration measures how fast an object's linear motion is changing.

What is the formula for calculating angular acceleration?

The formula for angular acceleration is: α = (ω₂ - ω₁) / t, where α is the angular acceleration, ω₂ is the final angular velocity, ω₁ is the initial angular velocity, and t is the time interval.

Can angular acceleration be negative?

Yes, angular acceleration can be negative. This means that the object is decelerating or slowing down its rotational speed.

How does the angular acceleration of a disk affect its motion?

The angular acceleration of a disk determines how quickly it will change its rotational speed. A larger angular acceleration will result in a faster change in rotational speed, while a smaller angular acceleration will result in a slower change in rotational speed.

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