Rocket: conservation of momentum

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Homework Help Overview

The discussion revolves around a problem involving the conservation of momentum in the context of a fireworks rocket that breaks into two pieces. The original poster presents a scenario where the rocket, initially moving at 45.0 m/s, splits into two equal mass pieces with unknown velocities v1 and v2.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the application of the conservation of momentum principle and question the validity of the original poster's approach, particularly the introduction of angles without clear context. Some suggest that the complexity of the problem may stem from the nature of the rocket's breakup.

Discussion Status

There is an ongoing exploration of the problem, with participants providing guidance on the need for clearer problem statements and suggesting the use of diagrams. Multiple interpretations of the breakup scenario are being considered, and some participants are questioning the assumptions made in the original calculations.

Contextual Notes

Participants note that the original problem does not specify the angles used in the calculations, leading to confusion. There is also a suggestion that the nature of the breakup (e.g., internal explosion vs. simple division) could significantly affect the outcome.

Np14
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Homework Statement


A fireworks rocket is moving at a speed of 45.0 m/s. The rocket suddenly breaks into two pieces of equal mass, which fly off with velocities v1 and v2. What are the magnitudes of v1 and v2?

Homework Equations


Conservation of Momentum
m1v1 + m2v2 = m1vo1 + m2vo2

The Attempt at a Solution


v1 = 45cos30° = 38.97
v2 = 45cos60° = 22.55

45 m/s ≠ 61.47 m/s

I have a feeling this problem is a lot more complicated, but I am not sure how to solve it.
 

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Np14 said:

Homework Statement


A fireworks rocket is moving at a speed of 45.0 m/s. The rocket suddenly breaks into two pieces of equal mass, which fly off with velocities v1 and v2. What are the magnitudes of v1 and v2?

Homework Equations


Conservation of Momentum
m1v1 + m2v2 = m1vo1 + m2vo2

The Attempt at a Solution


v1 = 45cos30° = 38.97
v2 = 45cos60° = 22.55

45 m/s ≠ 61.47 m/s

I have a feeling this problem is a lot more complicated, but I am not sure how to solve it.
Your problem statement makes no mention of 30 and 60 degrees yet you introduce them in your solution. I think you should draw a diagram and do a better job of stating the problem.
 
Answer depends on what caused the rocket to break up. If it was an internal explosion then the answer depends on how severe the explosion was. If it just broke in two, what would v1 and v2 be?
 
Np14 said:
have a feeling this problem is a lot more complicated
Yes, your method has no logic to it. Why should the speeds be given by those expressions?
Use the conservation equation you quoted, once in the original direction and once at right angles to that.
 
Np14 said:

Homework Statement


A fireworks rocket is moving at a speed of 45.0 m/s. The rocket suddenly breaks into two pieces of equal mass, which fly off with velocities v1 and v2. What are the magnitudes of v1 and v2?

Homework Equations


Conservation of Momentum
m1v1 + m2v2 = m1vo1 + m2vo2

The Attempt at a Solution


v1 = 45cos30° = 38.97
v2 = 45cos60° = 22.55

p1 = 2m x 45 cos30° = 2m x 38.97
p2 = 2m x 45 cos60° = 2m x 22.55

45 m/s ≠ 61.47 m/s

I have a feeling this problem is a lot more complicated, but I am not sure how to solve it.
 

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