Solving Collisions Problem: Velocity of Third Fragment

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Homework Help Overview

The problem involves a 600 kg cannon that explodes into three fragments, with two fragments having known masses and velocities. The task is to determine the velocity of the third fragment using principles of momentum conservation.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the application of momentum conservation and vector addition to find the missing velocity. Some express uncertainty about the use of trigonometry and vector sums, while others reference the Pythagorean theorem to calculate the resultant velocity.

Discussion Status

The discussion includes various attempts to solve the problem, with some participants confirming calculations while others question the consistency of diagrams and equations. There is an exploration of different methods to approach the problem, but no consensus has been reached on the final answer.

Contextual Notes

Participants are working under the constraints of homework rules, which may limit the extent of guidance provided. There are indications of confusion regarding the setup and calculations, particularly related to vector directions and resultant forces.

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Homework Statement



a 600 kg canon, initially at rest, exploded upon firing and broke into three fragments. One fragment of mass of 200 kg traveled east at 40m/s and a second fragment of mass 300 kg traveled due south at 20 m/s. What was the velocity of the third fragment?

Homework Equations



sum of P = sum of P'
0= P1 + P2 + P3

The Attempt at a Solution



I'm not sure whether I'm supposed to use trig or something to find the missing velocity.
Any help would be GREATLY appreciated.
 
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bondgirl007 said:

Homework Statement



a 600 kg canon, initially at rest, exploded upon firing and broke into three fragments. One fragment of mass of 200 kg traveled east at 40m/s and a second fragment of mass 300 kg traveled due south at 20 m/s. What was the velocity of the third fragment?

Homework Equations



sum of P = sum of P'
0= P1 + P2 + P3

The Attempt at a Solution



I'm not sure whether I'm supposed to use trig or something to find the missing velocity.
Any help would be GREATLY appreciated.
Momentum is a vector quantity, and as such, the sum of the momenta must obey the laws of vector additions. Are you familiar with resultants and vector sums?
 
This is what I have so far. Am I on the right track?
Will the resultant be the hypotenuse?

http://img408.imageshack.us/my.php?image=physicsay5.jpg
 

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I did Pythragoras to find the missing vector.

(8000)^2 + (6000)^2 = c^2
c=100 m/s

tan[tex]\theta[/tex] = 6000/8000
[tex]\theta[/tex] = 37

I got 100 m/s for my velocity and 37 degrees N of W. Is this right?
 
You know anythin about momentum conservation?
 
bondgirl007 said:
I did Pythragoras to find the missing vector.

(8000)^2 + (6000)^2 = c^2
c=100 m/s

tan[tex]\theta[/tex] = 6000/8000
[tex]\theta[/tex] = 37

I got 100 m/s for my velocity and 37 degrees N of W. Is this right?
Yes, that is correct, but your diagram and equation are not consistent with this answer. Looks like you combined a step when solving for 'c' , and the direction of the diagonal is wrong.
 

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