# Vector Diagram of Impulse: Is My Drawing Correct?

• songoku
In summary, the conversation discusses the correct vector diagram for a collision problem involving two objects. The question of which Δp should be shown in the diagram is raised, and it is ultimately determined that the correct option is the one showing ##\vec{p_1} + \vec{\Delta p} = \vec{p_1}'## with ##\vec{\Delta p}## representing the collision impulse experienced by object ##m_1##. The conversation also touches on the concept of vector subtraction in this context.
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

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).##

songoku
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 and Orodruin
Thank you very much kuruman and robphy

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.

songoku said:
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.

Last edited:
songoku
neilparker62 said:
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.

songoku and 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!

songoku

## 1. What is a vector diagram of impulse?

A vector diagram of impulse is a graphical representation of the change in momentum of an object over time. It shows the direction and magnitude of the impulse, which is the force applied to an object over a specific period of time.

## 2. How is a vector diagram of impulse different from a force diagram?

A force diagram shows the individual forces acting on an object, while a vector diagram of impulse shows the overall change in momentum due to those forces. In other words, a force diagram represents the cause of the change in momentum, while a vector diagram of impulse represents the effect.

## 3. What is the significance of the direction of the vector in a vector diagram of impulse?

The direction of the vector in a vector diagram of impulse represents the direction of the change in momentum. This is important because it tells us whether the object is gaining or losing momentum, and in which direction it is moving.

## 4. How can a vector diagram of impulse be used to analyze a collision?

A vector diagram of impulse can be used to analyze a collision by showing the change in momentum of the objects involved. This can help determine the forces involved in the collision and the resulting motion of the objects.

## 5. What are some real-world applications of vector diagrams of impulse?

Vector diagrams of impulse are commonly used in physics and engineering to analyze collisions, impacts, and other situations involving changes in momentum. They are also used in sports science to analyze the forces and movements involved in athletic activities.

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