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mhz
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Homework Statement
Two objects, X and Y, are held at rest on a horizontal frictionless surface and a spring is
compressed between them. The mass of X is 2/5 times the mass of Y. Immediately after the
spring is released, X has a kinetic energy of 50 J and Y has a kinetic energy of:
A. 20 J
B. 8 J
C. 310 J
D. 125 J
E. 50 J
Homework Equations
p = p'
E_kinetic = 1/2 mv^2
The Attempt at a Solution
Alright, if I use p = p' to set up an explosion/recoil equation where we have two variables v1' and v2' then I can use the kinetic energy equation to find v1' (50 = 1/2 (2/5) v1^2) and then plug this value into the p = p' equation, finding v2'. I then use v2' to find it's kinetic energy which should be the answer to the question and I get 20 J.
Apparently this is incorrect. How?
Please provide proof as to how I could possibly be wrong. Thanks :)