Trying to find Velocity and Kinetic Energy

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Homework Help Overview

The problem involves a 4.0 kg mess kit that explodes into two parts on a frictionless surface, with the goal of finding the original speed of the mess kit and the kinetic energy added by the explosion. The subject area includes concepts of momentum and kinetic energy in physics.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to apply kinetic energy equations to the problem and questions the role of non-conservative work in the context of the explosion. Other participants question which physical quantity is conserved during the explosion, leading to a discussion about momentum conservation.

Discussion Status

The discussion is actively exploring the conservation of momentum versus energy, with participants questioning the correctness of the original poster's approach and considering alternative perspectives. There is no explicit consensus yet, but the dialogue is focused on clarifying the relevant principles.

Contextual Notes

Participants are navigating the implications of an explosion in a frictionless environment, which may influence their understanding of energy conservation and the definitions of the involved quantities.

Rhaen
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The problem is as follows:

A 4.0 kg mess kit sliding on a frictionless surface explodes
into two 2.0 kg parts, one moving at 3.0 m/s, due north, and
the other at 5.0 m/s, 30 degrees north of east. (a) What is
the original speed of the mess kit. (b) How much kinetic
energy was added to the mess kit by the explosion?

I don't know exactly how to get started with this though I know that there would not be any potential energy so we would have the equation:

K_1 = K_2
(1/2)m_1(V^2) = (1/2)m_2(V^2)

But because the explosion adds kinetic energy to the equation through a non-conservative force we would have the equation:

K_1 + W_nc = K_2
(1/2)m_1(V^2) + W_nc = (1/2)m_2(V^2)

Is this correct in my understanding and if so, where would I go from here to get the original velocity? Thank you very much for your time.

-Rhaen-
 
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Which quantity is conserved here?
 
Last edited:
It would be the left hand side that is conserved which would make:

(1/2)m_1(V^2) = (1/2)m_2(V^2) + W_nc

But what would I do after that if that is the correct equation?

-Rhaen-
 
I was thinking more of momentum.
 

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