# Question on impulse

1. Oct 3, 2006

### mikefitz

If I'm given an object with X mass that is moving in one direction at Y velocity, then changes direction and moves at Z velocity, how do I calculate the impulse? Most equations I have are concerned with time intervals; this one is not.

2. Oct 3, 2006

The impulse equals the change of linear momentum.

3. Oct 3, 2006

### QuantumCrash

Impulse
= Change of momentum
= Final momentum - initial momentum
= mv - mu
= m(v-u)
= X (-Z-Y)

Assuming what you are talking about is linear momentum. I would be a lot more complicated and you would have to calculate is as an oblique collision if it were not.

4. Oct 4, 2006

### mikefitz

say the object moves at 3.6 m/s initially, then gets hit and moves -24.2 m/s in the other direction; m=.41kg

3.6(.41)=1.476
-24.2(.41)=-9.922

=-8.446 <--is this right?

5. Oct 4, 2006

### Staff: Mentor

No, impulse equals change in momentum, which is final minus initial.

6. Oct 5, 2006

### QuantumCrash

It is best you don't try to calculate the values of the momentum separately. Just calculate it using the formula I gave. The result you would get will be the sum of the magnitudes, not what you got.

7. Oct 5, 2006

### Staff: Mentor

The only mistake mikefitz made was not subtracting correctly.