# Explosion of one mass into three

1. Feb 22, 2009

### haroldham

1. The problem statement, all variables and given/known data
A 4.2 kg object, initially at rest, "explodes" into 3 objects of equal mass. Two of these are determined to have velocities of equal magnitudes (5.0 m/s) with directions that differ by 90 degrees. How much kinetic energy was released in the explosion? (that is what is the energy of the three object systems after the explosions)

2. Relevant equations

To be honest, my teacher did not cover this in class so I'm naked in the dark on this one.

3. The attempt at a solution

Since they are at 90 degrees to eachother, one would be 5 j m/s and the other would be 5 i m/s. I am not sure where to go from there or where the third factors in.

2. Feb 22, 2009

### LowlyPion

Since the center of mass remains the same from conservation of momentum, then first figure the velocity of the third object. (Happily you can because you know the mass of all 3 pieces are equal.)

Then you know how much KE each piece has since you know their masses and velocities.

3. Feb 22, 2009

### haroldham

Ok, thank you so much. I undertand.

4. Feb 23, 2009

### haroldham

Did you get 103.5 J?

5. Feb 23, 2009

### LowlyPion

Perhaps you should show your calculation?