Velocity of the center of mass in constrained motion

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Homework Help Overview

The discussion revolves around determining the velocity of the center of mass in a constrained motion scenario. Participants are exploring the relationship between the velocities of different points and the implications of their calculations.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are attempting to derive the velocity of point A based on the position of point B and are questioning the correctness of their results. There are discussions about resolving components of velocity and the distinction between speed and velocity. Some participants are exploring the geometric relationships involved.

Discussion Status

The discussion is active, with participants providing guidance on how to approach the problem through equations and geometric considerations. Multiple interpretations of the motion and relationships between points are being explored, but there is no explicit consensus on the final answer or direction of the velocity.

Contextual Notes

There are indications that participants are working under constraints related to homework guidelines, such as the need to specify direction when discussing velocity. The discussion also reflects uncertainty regarding the correct interpretation of the motion involved.

Prabs3257
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Homework Statement
In the figure shown A and B are two blocks of mass 5 kg each they are restraint to move in horizontal and vertical direction respectively as shown in the figure they are connected by a rigid massless rod as shown in the figure P is the midpoint of the rod when the velocity of B E is 4 upwards then the speed of of p at this instant is
Relevant Equations
Vcom = m1v1+m2v2/m1+m2
I tried getting the velocity of a which by using constraint came out to be 3 and by using the eqn for vcom i got the ans as 3.5 i just want to confirm is this the correct answer
 

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I don't think you have the right answer. Write an equation for the position of A as a function of the position of B. Then find the velocity of A as a function of the velocity of B. How is the horizontal velocity component of P related to the velocity of A? How is the vertical velocity component of P related to the velocity of B?
 
tnich said:
I don't think you have the right answer. Write an equation for the position of A as a function of the position of B. Then find the velocity of A as a function of the velocity of B. How is the horizontal velocity component of P related to the velocity of A? How is the vertical velocity component of P related to the velocity of B?
is the ans 2.5 coz i think i got the vcom wrong but now if we like resolve the component of vcom in x and y and calculate vcomx and vcomy separately and just take the resultant i think then it should be correct??
 
Prabs3257 said:
is the ans 2.5 coz i think i got the vcom wrong but now if we like resolve the component of vcom in x and y and calculate vcomx and vcomy separately and just take the resultant i think then it should be correct??
Yes, 2.5 m/s. But the question should not describe this as a velocity - it is a speed. For velocity a direction should also be specified. Can you see what the direction would be? Hint: consider the distance from P to the origin.
 
haruspex said:
Yes, 2.5 m/s. But the question should not describe this as a velocity - it is a speed. For velocity a direction should also be specified. Can you see what the direction would be? Hint: consider the distance from P to the origin.
I don't know the direction can you please explain it to me
 
Prabs3257 said:
I don't know the direction can you please explain it to me
What is the locus of P?
 
haruspex said:
What is the locus of P?
I am guessing maybe its a straight line
 
Prabs3257 said:
I am guessing maybe its a straight line
Try googling "trammel of archimedes" and watch how the center of mass moves.
 
Prabs3257 said:
I am guessing maybe its a straight line
Consider the triangle APO (where O is the point at the bottom right corner). What shape would you call it? What does that tell you about the distance OP?
 

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