Conservation of Momentum Question

[NoobeAtPhysics]

Homework Statement

We are learning momentum in physics class and I am having problems with this question.

i) An object at rest explodes into three pieces. Immediately after the explosion, two pieces have momenta given by F and A. Which vector describes the momentum of the third piece?

ii) An object at rest explodes into three pieces. Immediately after the explosion, two pieces have momenta given by B and C. Which vector describes the momentum of the third piece?

iii) An object at rest explodes into three pieces. Immediately after the explosion, two pieces have momenta given by D and E. Which vector describes the momentum of the third piece?

iv) An object moving with momentum E explodes into three pieces. Immediately after the explosion, two pieces have momenta given by V and D. Which vector describes the momentum of the third piece?

v) An object moving with momentum G explodes into three pieces. Immediately after the explosion, two pieces have momenta given by B and D. Which vector describes the momentum of the third piece?

Homework Equations

p=m*v

The Attempt at a Solution

i) C

ii) G

iii) A

iv) Hard one, R., I believe

v) C, I believe


/thank you/
noobe

 

[NascentOxygen]

i) An object at rest explodes into three pieces. Immediately after the explosion, two pieces have momenta given by F and A. Which vector describes the momentum of the third piece?

We need this and the other 3 parts to each be accompanied by a scaled diagram so we can check whether you are doing it correctly.

I agree with C here.

ii) An object at rest explodes into three pieces. Immediately after the explosion, two pieces have momenta given by B and C. Which vector describes the momentum of the third piece?

I don't agree with your answer.

Diagrams please.

 

[NoobeAtPhysics]

Hmm, do I have to measure each angle then use the formula?

Is there a way to look at it visually?

 

[NascentOxygen]

Graphically. You trace the lines, so you get length and angle correctly, and add vectors graphically on paper.

 

[Nickie]

As a scientist, my response would be to make sure you understand the concept of conservation of momentum before attempting to answer these questions. Conservation of momentum states that the total momentum of a system remains constant before and after an interaction or event. This means that the total momentum of the three pieces after the explosion must be equal to the momentum of the original object before the explosion.

For i) and ii), the third piece has a momentum equal in magnitude but opposite in direction to the total momentum of the other two pieces. So for i), the third piece would have a momentum of -F-A and for ii), the third piece would have a momentum of -B-C.

For iii), the total momentum after the explosion must be equal to the momentum of the original object, so the third piece would have a momentum of -D-E.

For iv), since the original object was already moving with momentum E, the third piece would have a momentum of -V-D-E.

For v), the third piece would have a momentum of -B-D-G.

Remember, momentum is a vector quantity, so direction matters when calculating the total momentum of a system. I would also recommend practicing more problems and seeking help from your teacher or peers if you are still having trouble. Good luck with your homework!