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Homework Statement
In the attachment problem i was able to find the final velocity, from there someone helped me and got a formula that really confuses me. μ(m + M)g *x = 1/2(m + M) v^2
Homework Equations
All the work is write and the answer i just dont understand how they got
μ(m + M)g *x = 1/2(m + M) v^2
The Attempt at a Solution
The mass of the bulet m = 125g = 0.125kg
the mass of the block M = 5kg
the speed of the bullet vi = 300m/s
from law of conservation of momentum
mvi = (m + M)vf
then vf = mvi / (m + M)
= (0.125)(300)/(0.125 + 5)
= 7.32 m/s
Now from work energy theorem
W = ΔK
μ(m + M)g *x = 1/2(m + M) v^2
therefore the distance traveled
x = v^2 / μg = (7.32)^2 / (0.25)(9.8)(2) = 10.9 m
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