Rotational Dynamics and torque, easy problem

In summary, the conversation discusses the calculation of angular acceleration of a rectangle when a torque of 13 Nm is applied about different axes. The person asking the question is unsure of how to approach the problem and mentions using the formula t=Ia, but gets the wrong answer. They also mention the answers for each axis are (a)2.4 (b)5.1 (c)3.0. It is also mentioned that it is unclear whether the object is forced to rotate on the mentioned axes. The conversation ends with a request for help in calculating the moment of inertia of the object about the x, y, and z axes. There is also some confusion about whether the axes rotate with the system or around the center
  • #1
new324
30
0
I really have no idea how to go about doing this one... Any help is well appreciated! Thanks!

What is the angular acceleration of the rectangle in (attachment) if a torque of 13 Nm is applied about (a) the x-axis (b) the y-axis and (c) the z axis (through origin and perpendicular to the page).

I assumed I would use t=Ia where I would simply be m*r^2. But that gives me the wrong answer.

The answers are (a)2.4 (b)5.1 (c)3.0 if that helps.
 
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  • #2
This question is a bit obnoxious because it's unclear whether the object is forced to rotate on the axes you meantion.

Regardless, can you calculate the moment of inertia of the object about the x,y, and z axes of the object?
 
  • #3
I assumed the axes rotated with the system (around the center of the rectangle). But then I guess the radius would be the same and the angular acceleration would just be equal and opposite for (a) and (b) (clockwise and counterclockwise rotation). And all I really know about calculating moment of inertia is plugging what's given (or found) in a problem into a given set of I's provided in class. Your right this is kind of an iffy system...Sorry. But thanks anyways!
 

Related to Rotational Dynamics and torque, easy problem

1. What is rotational dynamics and torque?

Rotational dynamics is the study of the motion of objects that are rotating or spinning around an axis. Torque is the measure of the force that causes an object to rotate.

2. How is torque calculated?

Torque is calculated by multiplying the force applied to an object by the distance between the point of application and the axis of rotation. It is measured in Newton-meters (N*m) in the metric system.

3. What is the difference between linear and rotational motion?

Linear motion refers to the movement of an object along a straight line, while rotational motion refers to the movement of an object around a fixed axis. In linear motion, the velocity and acceleration are in the same direction, while in rotational motion, they are perpendicular to each other.

4. How does torque affect rotational motion?

Torque is responsible for the acceleration of an object in rotational motion. The larger the torque, the greater the acceleration of the object. It also determines the direction of rotation, with a counterclockwise torque causing a counterclockwise rotation and vice versa.

5. Can you provide an example of a real-life application of rotational dynamics and torque?

One example is the use of torque in opening a door. The force applied to the doorknob creates a torque that causes the door to rotate around its hinges. The larger the force applied, the greater the torque and the easier it is to open the door.

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