Disk on a Motion: Find the Coordinates of Point A at t= 4piR/v

In summary, the problem involves a disk placed on a frictionless x-y plane with initial motion given at t=0. The point A(R,0) has a velocity towards +ve x-axis and ω=v/2R. The task is to find the coordinates of Point A at t=4piR/v. The equations needed for this problem are ∅=ωt and the motion of A can be expressed as a function of velocity of the center and ω. It may be easier to calculate the motion of A using w, ω for the center and then relate it to the center of mass velocity.
  • #1
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Homework Statement



Adisk of radius R centred at the origin is placed on a frictionless x-y plane with origin as the centre of the disk.At t=0, the disk is given initial motion such that the point A(R,0) has velocity v towards
+ve x-axis and ω=v/2R. Find the coordinates of Point A at t= 4piR/v

Homework Equations



∅=ωt..That's all i think is needed

The Attempt at a Solution


i used but i am getting a wrong answer help!
 
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  • #2
Can you express the motion of A as functtion of the velocity of the center and ω?
Based on that, can you calculate this velocity and ω?
 
  • #3
That's the problem..The velocity of A at t=0 is given..How can i relate to the centre of mass velocity..
 
  • #4
I proposed to start with the other direction (use w,ω for the center and calculate the motion of A as function of those variables) for a good reason - it is easier.
Did you try to calculate it?
 
  • #5


As a scientist, my response to this content would be as follows:

The problem statement describes a disk of radius R that is initially moving with a velocity v towards the positive x-axis, with an angular velocity ω=v/2R. The goal is to find the coordinates of Point A, located at (R,0), at a specific time t= 4piR/v.

To solve this problem, we can use the equation ∅=ωt, where ∅ is the angular displacement and t is the time. We know that at t=0, the disk is at its starting position and therefore, the angular displacement is also 0. We can then set up the following equation:

0=ωt= (v/2R)t

Solving for t, we get t=0. This means that at t= 4piR/v, the disk will have completed 4piR/v radians of rotation. To find the coordinates of Point A at this time, we can use basic trigonometry. The x-coordinate of Point A will be R*cos(4piR/v) and the y-coordinate will be R*sin(4piR/v). Therefore, the coordinates of Point A at t= 4piR/v are (R*cos(4piR/v), R*sin(4piR/v)).

It is important to double-check our answer to ensure it makes sense. We can see that at t=0, the disk is at its starting position and therefore, Point A is at (R,0). As time passes, the disk rotates counterclockwise and Point A will move along the circumference of the disk. At t= 4piR/v, the disk will have completed one full rotation (2pi radians) plus an additional 2piR/v radians. This means that Point A will have moved to the point directly opposite its starting position, which matches our solution.

In conclusion, the coordinates of Point A at t= 4piR/v are (R*cos(4piR/v), R*sin(4piR/v)). It is important to carefully analyze the given information and use appropriate equations to solve the problem. If you are getting a wrong answer, double-check your calculations and make sure you are using the correct equations and units.
 

FAQ: Disk on a Motion: Find the Coordinates of Point A at t= 4piR/v

What is a "Disk on a Motion"?

A Disk on a Motion refers to a circular object that is moving in a certain direction. This can be seen as a simplified version of a rotating disk, where the motion is along a single axis.

What does "t= 4piR/v" represent in the equation?

The "t= 4piR/v" represents the time at which we are trying to find the coordinates of Point A. In this equation, R represents the radius of the disk and v represents the velocity of the disk.

How do you find the coordinates of Point A?

To find the coordinates of Point A at a specific time, we need to use the equation x= Rcos(ωt) and y= Rsin(ωt), where ω represents the angular velocity. Plug in the values of R, ω, and the given time t to find the x and y coordinates of Point A.

What if the disk is not moving at a constant velocity?

If the disk is not moving at a constant velocity, the equation for finding the coordinates of Point A will be more complex. We would need to use calculus to find the position at a specific time. However, if the velocity is changing at a constant rate, we can still use the same equation by finding the average velocity over the given time interval.

Can this equation be applied to any shape other than a disk?

No, this equation is specifically for a circular disk. For other shapes, the equation for finding the coordinates at a specific time will be different.

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