EENGA 2019 Momentum question -- collision of two masses

AI Thread Summary
The discussion centers on calculating the total energy loss after a collision involving two masses. Participants are debating the correct answer choice, with one consistently arriving at option C instead of the correct answer, B. The confusion arises from the use of different masses in the equations, specifically the moving particle's mass versus the stationary particle's mass. Clarification is sought on how to manipulate the equations to match the answer choices, particularly in expressing the results as a single fraction. The conversation emphasizes the importance of correctly identifying and using the relevant masses in the calculations.
adz7861
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Homework Statement
Expression for the total loss of energy after the collision
Relevant Equations
p=mv
KE=1/2mv^2
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adz7861 said:
Homework Statement:: Expression for the total loss of energy after the collision
Relevant Equations:: p=mv
KE=1/2mv^2

View attachment 272111

View attachment 272113
Ok, but which option does that match?
 
haruspex said:
Ok, but which option does that match?

I keep getting my answer to be C, when the real answer is B
 
adz7861 said:
I keep getting my answer to be C, when the real answer is B
Then you are making a mistake beyond the working you posted. What you posted matches B.
 
haruspex said:
Then you are making a mistake beyond the working you posted. What you posted matches B.
The only difference in B & C are the different masses on the nominator. What I've got is the mass of the moving particle (mE) as the nominator. The answer states that it should be ME which is the mass of the stationary particle.
So my working out must be incorrect, unless I'm missing a further step.

I've basically done the KE after the collision - KE before collision to give me a value for the energy loss. I am confused on what to do further after my last equation.
 
adz7861 said:
The only difference in B & C are the different masses on the nominator. What I've got is the mass of the moving particle (mE) as the nominator. The answer states that it should be ME which is the mass of the stationary particle.
So my working out must be incorrect, unless I'm missing a further step.

I've basically done the KE after the collision - KE before collision to give me a value for the energy loss. I am confused on what to do further after my last equation.
Can you subtract fractions?
Write the second term as a fraction with denominato m+M. Show your working.
 
adz7861 said:
unless I'm missing a further step.
Exactly. Get your answer into the form of the choices, a single fraction.
 

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