Rotation and curl? (Vector calc)

In summary, a rigid body with rotation but not curl would be one that is rotating but not experiencing any change in its velocity field. An example of this could be a spinning top. A rigid body with curl but not rotation would be one that is not rotating but has a non-zero curl in its velocity field. An example of this could be a fluid flow over a stationary obstacle. A rigid body with both rotation and curl would be one that is both rotating and experiencing a change in its velocity field. An example of this could be a spinning wheel rolling down a hill. A rigid body with neither rotation nor curl would be one that is not rotating and has a zero curl in its velocity field. An example of this could
  • #1
calculusisrad
20
0

Homework Statement


Give an example of a rigid body that has:
Rotation but not curl
Curl but not rotation
Rotation and curl
Neither rotation nor curl

The Attempt at a Solution


i don't even get what rotation is. Or curl, to be honest...*sigh* Maybe if you help me I can begin to understand. My book is making me want to bash myself over the head, it's so unhelpful x(
 
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  • #2
Curl only applies to vector fields. The only vector field associated with a rigid body that you can take a curl of is the velocity field. Curl of a velocity field of a rigid body is simply proportional to the angular velocity of said body. So a rigid body is either rotating and has curl of velocity field, or it is not rotating and has zero curl of velocity field. With fluids you can get more creative, but with rigid bodies, these are your options. So I'm not sure the question makes sense. It's almost like answer to one of the questions, rotating rigid body, was accidentally put into the question, making the rest of it nonsensical.

Or I could be missing something. But it doesn't make any sense to me.
 
  • #3
It says for a rigid body or fluid in motion...
I think she wants real world examples... I agree that it is confusing
 

What is the concept of rotation in vector calculus?

Rotation, also known as angular velocity, is a measure of how much a vector field is rotating around a specific point. In other words, it is the amount of twist or spin that a vector field has at a given point.

How is rotation different from curl in vector calculus?

Rotation measures the overall rotation of a vector field, while curl measures the amount of local rotation at each point in the field. In other words, rotation gives a global picture of the field, while curl gives a more detailed view of the field at each point.

What is the mathematical formula for calculating rotation and curl?

The mathematical formula for calculating rotation is given by the cross product of the gradient operator and the vector field. The formula for calculating curl is given by the dot product of the del operator and the vector field. In vector notation, this can be written as ∇ x F for rotation and ∇ · F for curl.

What are some real-world applications of rotation and curl?

Rotation and curl have various applications in physics, engineering, and fluid mechanics. For example, they are used to model the motion of fluids, analyze electromagnetic fields, and predict the behavior of rotating objects such as turbines or helicopter blades.

How can I visualize rotation and curl in a vector field?

One way to visualize rotation and curl is by using vector field plots or vector field animations. These visual representations show the direction and magnitude of the vector field at different points, making it easier to understand the concepts of rotation and curl.

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