Rotational motion with inertial forces

In summary, the conversation discusses the forces acting on a mass on an incline in a rotating frame of reference. The forces include gravity, normal force, friction, centripetal acceleration, and Coriolis acceleration. The block must not slip according to the exercise, so there is no Coriolis force in this case. The forces acting on the block in the rotating frame are centripetal and centrifugal.
  • #1
OnAHyperbola
29
12

Homework Statement


Capture.PNG


Homework Equations



Centripetal acceleration$$=\omega ^2R$$
Coriolis acceleration $$=2v_{rot}\omega $$

The Attempt at a Solution


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Think of the mass as lying on an incline. The forces I know are parallel to the incline are $$mgsin(\alpha), \mu N$$
Forces I know are perpendicular to the incline are $$mgcos(\alpha),N$$. What I'm unsure about is how to deal with centripetal and coriolis forces. Could someone shed some light on this?
 
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  • #2
Hi,
Does the block move in the rotating frame of reference ? So what about the Coriolis force ?
 
  • #3
As seen by an observer relative to whom the cylinder is rotating, the block is stationary. That must mean that it is moving in the rotating frame of reference. So there must be a Coriolis force on the block, right? I don't think there is any centripetal force on the block in the rotating frame.
 
  • #4
The exercise wants you t find ##\omega##s for the case the block does not slip !
 
  • #5
Yes, does not slip relative to a stationary observer who sees the cylinder as rotating. I can see that.
 
  • #6
More imporantly: "stays still wrt the rotating cylinder" !
 
  • #7
Oh..so it is rotating... No coriolis force in that case, just centripetal and centrifugal (in the block's frame) then?
 
  • #8
Yes. Some gravity and some friction too :smile:
 

1. What is rotational motion with inertial forces?

Rotational motion with inertial forces refers to the movement of an object around a fixed axis, while experiencing forces that oppose the motion and are caused by the object's own inertia. This occurs when an object is rotating and experiences a centripetal force, which is directed towards the center of rotation.

2. What is the difference between rotational motion with inertial forces and uniform circular motion?

The main difference between these two types of motion is the presence of inertial forces. In uniform circular motion, there are no inertial forces acting on the object, while in rotational motion with inertial forces, there are forces acting on the object due to its own inertia. Additionally, uniform circular motion occurs at a constant speed, while rotational motion with inertial forces can involve changes in speed or direction.

3. How do you calculate the magnitude of inertial forces in rotational motion?

The magnitude of inertial forces in rotational motion can be calculated using the equation F = mω²r, where F is the inertial force, m is the mass of the object, ω is the angular velocity, and r is the distance from the object to the axis of rotation. This equation is derived from Newton's second law of motion, which states that the force acting on an object is equal to its mass multiplied by its acceleration.

4. Can rotational motion with inertial forces cause objects to move in a curved path?

Yes, rotational motion with inertial forces can cause objects to move in a curved path. This is because the inertial forces act as a centripetal force, which is necessary to keep an object moving in a circular or curved path. Without this force, the object would continue moving in a straight line tangent to its circular path.

5. What are some real-life examples of rotational motion with inertial forces?

Some common examples of rotational motion with inertial forces include a spinning top, a rotating merry-go-round, and a swinging pendulum. In each of these cases, the object is rotating around a fixed axis and experiences forces due to its own inertia, such as centripetal force and centrifugal force.

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