EENGA 2019 Momentum question -- collision of two masses

[adz7861]

Homework Statement

Expression for the total loss of energy after the collision

Relevant Equations

p=mv
KE=1/2mv^2

 

[haruspex]

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?

 

[adz7861]

Ok, but which option does that match?

I keep getting my answer to be C, when the real answer is B

 

[haruspex]

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.

 

[adz7861]

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.

 

[ehild]

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.

 

[haruspex]

unless I'm missing a further step.

Exactly. Get your answer into the form of the choices, a single fraction.