Vector Diagram of Impulse

[songoku]

Homework Statement

Object $m_1$ moves with velocity $v_1$ collides with object $m_2$ and has final velocity of $v_{1}^{'}$. Which vector diagram is correct?

Relevant Equations

I = Δp

I think all the options are wrong. Since I = Δp = m₁v₁^' - m₁v₁, I draw it like this:

Is my drawing wrong?

Thanks

 

[kuruman]

Your diagram is not different from one of the 5 choices (which one?) in the same manner that $A - B$ is not different from $A + (-B).$

 

[robphy]

At times, I think it is better to think of $\Delta \vec p=\vec p_f - \vec p_i$
implicitly but "physically"
as what has to be added to $\vec p_i$ to get $\vec p_f$: $$ \vec p_i + \Delta \vec p= \vec p_f$$

 

[songoku]

Thank you very much kuruman and robphy

 

[neilparker62]

From conservation of momentum, I would be looking for the diagram in which the vector representing $m_1v_1$ is the vector sum of the other two.

 

[neilparker62]

Homework Statement:: Object $m_1$ moves with velocity $v_1$ collides with object $m_2$ and has final velocity of $v_{1}^{'}$. Which vector diagram is correct?
Relevant Equations:: I = Δp

The question here is which $\vec{\Delta p}$ ? $\vec{\Delta p}$ experienced by $m_2$ or $\vec{\Delta p}$ experienced by $m_1$ ? Because they are equal and opposite.

Edited to show $\vec{\Delta p}$ as a vector.

 

[kuruman]

The question here is which $\Delta p$ ? $\Delta p$ experienced by $m_2$ or $\Delta p$ experienced by $m_1$ ? Because they are equal and opposite.

I too considered this ambiguity. I decided that it is the Δp of the object whose initial and final momenta are shown because the initial and final momenta of the target mass could be anything. I classified this as a vector subtraction problem.

 

[neilparker62]

Then the correct option is the one showing $\vec{p_1} + \vec{\Delta p} = \vec{p_1}'$ with $\vec{\Delta p}$ being the collision impulse experienced by mass $m_1$. In which case I stand corrected in respect of post #5 in which I assumed $\vec{\Delta p}$ is the collision impulse experienced by (also) assumed stationary object $m_2$. Tricky!