Solving Collisions Problem: Velocity of Third Fragment

[bondgirl007]

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.

 

[PhanthomJay]

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?

 

[bondgirl007]

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

 

[bondgirl007]

I did Pythragoras to find the missing vector.

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

tan$$\theta$$ = 6000/8000
$$\theta$$ = 37

I got 100 m/s for my velocity and 37 degrees N of W. Is this right?

 

[physixguru]

You know anythin about momentum conservation?

 

[PhanthomJay]

I did Pythragoras to find the missing vector.

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

tan$$\theta$$ = 6000/8000
$$\theta$$ = 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.