Need help in the physic HW question

[NasuSama]

Homework Statement

A bullet of mass m = 17.6 g traveling horizontally at speed vo = 565 m/s strikes a block of mass M = 678 g sitting on a frictionless, horizontal table. This time, however, it comes out the other side of the block at speed v = 524 m/s.

Calculate J, the magnitude of the impulse exerted by the bullet on the block.

2. Homework Equations

Hm...

Impulse = Momentum = Ft = mv_f - mv_i

3. The Attempt at a Solution

I think that the impulse is same as the momentum. I think that is...

Impulse = mv_f - mv_i

I got -0.722 but it's incorrect. My professor said that impulse can't be negative because time is positive and force is positive.

But it seems like I'm on the wrong path. (This is from the previous question. Seems like nobody wants to pay attention, so I ask again.)

 

[Flipmeister]

Impulse is the change in momentum during a collision. But the question's asking for the impulse on the bullet by the block, not the other way around. So you'll have to find the change in momentum of the block first.

 

[SammyS]

Homework Statement

A bullet of mass m = 17.6 g traveling horizontally at speed vo = 565 m/s strikes a block of mass M = 678 g sitting on a frictionless, horizontal table. This time, however, it comes out the other side of the block at speed v = 524 m/s.

Calculate J, the magnitude of the impulse exerted by the bullet on the block.

2. Homework Equations

Hm...

Impulse = Δ Momentum → Ft = mv_f - mv_i

3. The Attempt at a Solution

I think that the impulse is same as the momentum. I think that is...

Impulse = mv_f - mv_i

I got -0.722 but it's incorrect.

This is the impulse exerted on the bullet by the block.

My professor said that impulse can't be negative because time is positive and force is positive.

But it seems like I'm on the wrong path. (This is from the previous question. Seems like nobody wants to pay attention, so I ask again.)