Problem on frame of reference in rotation

In summary, when a disc of radius r rolls without slipping by half a revolution. Well I have taken a point on the circumference of the disc which is P which makes contact with the surface. The reference frame is fixed on it. Point Q lies on the diametrically opposite end on the disc.Hence as the disc rotates the frame of reference should also rotate and when it is turned by half the point Q will still appear on y-axis at distance of 2r.So my dilemma is if the position vector doesn't change with respect to a point on the disc so it should appear stationary with respect to P. then how come we can say that the velocity of P with respect to ground is towards left and of Q is towards
  • #1
shreyashebbar
11
0

Homework Statement



I wanted to know if I consider the frame of reference as a rotating body itself, then will the points lying on the body rotating be stationary with respect to the rotating frame of reference?

Homework Equations


None


The Attempt at a Solution



As per me, if I am sitting in a merry go round and my friend sitting on other side should appear stationary with respect to me as he is not changing his distance with respect to me.

Kindly help me with this dilemma ?
 
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  • #2
Hi shreyashebbar! :smile:

Think about a rod rotating about one of its ends, and take the reference frame to be the out-most point. Will all the points appear stationary to you? Take the innermost point(axial), will the whole body still appear stationary in that frame?
 
  • #3
shreyashebbar said:
As per me, if I am sitting in a merry go round and my friend sitting on other side should appear stationary with respect to me as he is not changing his distance with respect to me.
Correct.

Kindly help me with this dilemma ?
What dilemma?
 
  • #4
Hello,
when a disc of radius r rolls without slipping by half a revolution. Well I have taken a point on the circumference of the disc which is P which makes contact with the surface. The reference frame is fixed on it. Point Q lies on the diametrically opposite end on the disc.

Hence as the disc rotates the frame of reference should also rotate and when it is turned by half the point Q will still appear on y-axis at distance of 2r.

So my dilemma is if the position vector doesn't change with respect to a point on the disc so it should appear stationary with respect to P. then how come we can say that the velocity of P with respect to ground is towards left and of Q is towards right and hence velocity of p with respect to q is twice the velocity in case of pure rolling?
 
  • #5
You are confusing frames of reference here.

I suggest that you work on understanding physics from the perspective of inertial frames before you delve into using rotating frames.
 

Related to Problem on frame of reference in rotation

1. What is a frame of reference in rotation?

A frame of reference in rotation is a coordinate system that is used to describe the motion of an object that is rotating. It is used to determine the position, velocity, and acceleration of an object as it rotates around a fixed point.

2. How does the choice of frame of reference affect the analysis of rotational motion?

The choice of frame of reference can greatly affect the analysis of rotational motion. For example, if the frame of reference is chosen to be the center of rotation, then the object will appear to have zero angular velocity and acceleration. However, if the frame of reference is chosen to be a point outside of the rotating object, the object will appear to have both angular velocity and acceleration. Therefore, it is important to carefully choose the frame of reference for accurate analysis.

3. What is the difference between absolute and relative frames of reference in rotation?

An absolute frame of reference in rotation is a fixed coordinate system that is not affected by the motion of the rotating object. On the other hand, a relative frame of reference is attached to the rotating object and moves with it. The choice of frame of reference depends on the specific problem and what information is needed.

4. How is the Coriolis effect related to the frame of reference in rotation?

The Coriolis effect is a phenomenon that occurs due to the rotation of the Earth. It causes objects in motion to appear to be deflected from their straight path when viewed from a rotating frame of reference. This effect is important to consider in situations such as weather patterns and ocean currents, where the Earth's rotation is a significant factor.

5. Can the frame of reference in rotation ever be disregarded?

No, the frame of reference in rotation cannot be disregarded. It is an essential aspect of analyzing rotational motion and must always be carefully chosen in order to accurately describe the motion of a rotating object.

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