What is the velocity of each ball when the rod hits the ground?

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Homework Help Overview

The problem involves two heavy balls attached to a light metallic rod that falls to the ground. Participants are tasked with determining the velocity of each ball at the moment the rod impacts the floor, while neglecting the mass of the rod and friction between the balls and the floor.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the conservation of energy, with references to potential and kinetic energy. There are attempts to set up energy equations to find the velocity. Some participants question the clarity of the problem and whether a diagram is available. Others inquire about the orientation of the rod and the need to consider forces acting on the masses.

Discussion Status

The discussion is ongoing, with some participants providing insights into energy conservation principles while others seek clarification on the problem's setup. There is no explicit consensus on the interpretation of the problem, and multiple aspects are being explored.

Contextual Notes

Participants note the absence of a diagram and question the role of the normal force on the mass at the floor. The problem's description may lack sufficient detail for complete understanding.

cokezero
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Homework Statement



Two heavy balls of equal mass M are attached to the long but light metallic rod standing
on the floor. The rod with the balls falls to the floor. Find the velocity of each ball at the moment
when the rod hits the ground. Neglect mass of the rod and the friction between the balls and the
floor.


Homework Equations



E1=Ef
m1v1 + m2v2 = m1v1 + m2v2
E1 = mgh


The Attempt at a Solution



Mass 2 initial energy = mgh, mass 1(on floor) = 0
When rod falls Mass 2 = 0; mass 1 = 0.5mv^2
so mgh = 0.5mv^2

V=sqrt(2gh) ??
 
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Can you explain the problem better? Is there a diagram?

AM
 
You have to take into consideration all the energies that are present in this problem. When the dumbbell is at a certain height, it has potential energy. When the Dumbbell is acceleration towards the ground, it has kinetic energy. There you have your answer. As long as you set your potential energy equal to zero at the ground just make your before and after energies equal each other, mgh = (1/2)mv^2 and just solve for v.

Edit: Hmmm, I'm looking at your question again and maybe you didn't describe it well enough. Does the dumbbell hit the floor horizontally?
 
Yes the rod hits horizontally. Do I have to consider the normal force on the mass at the floor.

The Diagram is basically a vertical rod with one end on the floor and the other in the air. both ends have spherical masses attached to them.
 

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