Perpendicular inelastic collision problem

AI Thread Summary
The discussion centers on understanding the derivation of results in a perpendicular inelastic collision problem, specifically where the variable "v" is applied and subsequently disappears in the equations. Participants note that the textbook skips intermediate algebraic steps, which leads to confusion about how "v" is calculated and used in the final equations. The process involves solving a system of equations to find "v" as a function of the masses and initial velocities of the colliding objects. Additionally, a general formula for energy loss in one-dimensional inelastic collisions is mentioned, highlighting the role of reduced mass and relative velocity. Clarifying these steps is essential for grasping the underlying physics of the collision problem.
NODARman
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Homework Statement
Where did "v" go?
Relevant Equations
.
I still don't get it where did "v" go.
I'm trying to solve the problem that is on the second image.
1658833952271.png


Second image.
1658834059120.png
 
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Yes well your book doesn't show all the in between steps on how exactly it derives that result. It just states "Sparing the reader the algebra".

What is done in the in between steps (which you should try to work out by yourself, I ll just outline the steps) is that the system of equations 4.5.18 (two equations with two unknowns, the common velocity and the angle) is solved and then once you solve it and find ##v## (##v## will be a function of ##m_1,m_2, v_1,v_2##) then ##v## it is replaced in equation 4.5.19 and then after some algebra you end up with equation 4.5.20.
 
NODARman said:
Homework Statement:: Where did "v" go?
Relevant Equations:: .

I still don't get it where did "v" go.
I'm trying to solve the problem that is on the second image.
View attachment 304812

Second image.
View attachment 304813
There's a general result (which can be derived) for energy loss in a 1 dimensional inelastic (collide and coalesce) collision: $$\Delta E= \frac{1}{2} \mu \Delta v^2$$ where ##\mu## is the reduced mass of the colliding objects and ##\Delta v## their relative velocity: $$\mu = \frac{m_1m_2}{m_1+m_2}$$It looks like there's nothing different here except that ##\Delta v## is replaced by the vector difference of the two velocities.
 
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