Would The Position of the Center of Mass Change Position?

Click For Summary

Discussion Overview

The discussion revolves around the behavior of the center of mass of a uniform density bar when it is struck at the tip by a weight. Participants explore whether the center of mass would move as a result of this collision, considering aspects of angular and linear momentum.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • Some participants propose that if the bar only acquires angular momentum, its center of mass will not move, assuming it is initially at rest.
  • Others argue that in a realistic scenario, the bar will acquire linear momentum during the collision, leading to a displacement of the center of mass.
  • One participant questions whether this is a homework problem and seeks clarification on the forces acting on the bar during the collision.
  • Another participant expresses uncertainty about the relationship between the distance from the center of mass and the acceleration of the center of mass when a force is applied.
  • Some participants challenge the idea that the acceleration of the center of mass depends on the torque of the external force in relation to the center of mass.

Areas of Agreement / Disagreement

Participants do not reach a consensus; multiple competing views remain regarding the movement of the center of mass and the effects of applied forces.

Contextual Notes

There are limitations in the assumptions made about the initial conditions of the bar and the nature of the forces involved in the collision. The discussion also reflects uncertainty regarding the application of physics equations to support claims.

student34
Messages
639
Reaction score
21
Take a uniform density bar in space for example. Would the center of mass move if the bar was struck at the very tip perpendicularly by some weight?

If so, please explain.
 
Physics news on Phys.org
It depends. If the bar only acquires angular momentum, its center of mass will not move¹². But in any realistic situation, linear momentum will be acquired in this collision and the center of mass will be displaced.

¹] I am assuming the a center of mass is initially at rest.
²] If the bar was not of uniform density, the center of mass could have its position changed even by angular momentum alone.

Note that I am no physics adept.
 
student34 said:
Take a uniform density bar in space for example. Would the center of mass move if the bar was struck at the very tip perpendicularly by some weight?

If so, please explain.

Is this a homework problem?
What do you think? Is there a force on the bar during collision? What happens when a force acts on the bar?
 
mafagafo said:
It depends. If the bar only acquires angular momentum, its center of mass will not move¹². But in any realistic situation, linear momentum will be acquired in this collision and the center of mass will be displaced.

¹] I am assuming the a center of mass is initially at rest.
²] If the bar was not of uniform density, the center of mass could have its position changed even by angular momentum alone.

Note that I am no physics adept.

I only want to know for sure.
 
nasu said:
Is this a homework problem?

no

What do you think? Is there a force on the bar during collision? What happens when a force acts on the bar?

I am not sure, but I do know that the further away from the center of mass the force is the less acceleration the center of mass would have. I just have to imagine tapping the center of the bar with my finger and then tapping the end. So it does seem like the acceleration of the center of mass might go to zero when the force is at the very end of the bar. However, I don't know what physics equation proves this.
 
student34 said:
no

I am not sure, but I do know that the further away from the center of mass the force is the less acceleration the center of mass would have.
You may need to revise what you think you "know".
For example here:
http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/n2ext.html

The acceleration of the center of mass does not depend on the torque of the external force in respect to the center of mass.
 

Similar threads

Undergrad Do objects always rotate around center of mass?
  • · Replies 141 ·
5
Replies
141
Views
8K
Undergrad Lower center of mass creates more stability so how do you explain moving the center of mass upwards increases stability?
  • · Replies 4 ·
Replies
4
Views
1K
Undergrad Does Raising My Arm Change the Center of Mass?
  • · Replies 8 ·
Replies
8
Views
2K
Undergrad Question about a Rotating system with mass moving inwards
  • · Replies 19 ·
Replies
19
Views
3K
Undergrad Question about the velocity of the center of mass reference frame
  • · Replies 21 ·
Replies
21
Views
2K
Undergrad Solving for the trajectory of the center of mass
  • · Replies 1 ·
Replies
1
Views
1K
High School Calculate needed dimensions of table - Center of mass, levers etc
  • · Replies 11 ·
Replies
11
Views
3K
Undergrad A gravity conundrum involving a solid cylinder
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Center of Mass of a jetpack-Earth System
  • · Replies 7 ·
Replies
7
Views
3K
Graduate Oscillation of a boat in still water (Metacenter and Center of Mass)
  • · Replies 24 ·
Replies
24
Views
3K