Kinetic Energy of an arrow problem

AI Thread Summary
The discussion revolves around calculating the mass of an arrow that slows down while passing through an apple. The initial and final velocities of both the arrow and the apple are provided, along with the apple's mass. The initial attempt used kinetic energy equations, but the poster struggled to arrive at the correct mass. Another participant suggests using conservation of momentum instead of kinetic energy, highlighting that all necessary values are available for this approach. The conversation emphasizes the importance of selecting the right physics principle for solving the problem effectively.
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Homework Statement


An arrow slows down from 43 m/s to 28 m/s as it passes through an apple. If the 493-g apple was originally at rest and sped up to 0.44 m/s, what is the mass of the arrow

Vapple,i = 0 m/s
Vapple,f = 0.44 m/s
Varrow,i = 43 m/s
Varrow,f = 28 m/s
m,apple = o.493 kg
m,arrow = ?


Homework Equations



im guessing we only need Eki = Ekf which is 1/2mvi(ar)^2 + 1/2mvi(ap)^2 + 1/2mvf(ar)^2 + 1/2mvf(ap)^2

The Attempt at a Solution



i plugged it all into the equation so it looks like this near the end

924.5m = 0.0477224 + 392m

i then subtracted the 392 from 924.5 and divided that number by the long decimal to solve for m, but answer was totally off. can anyone tell me where i went wrong? thanks
 
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i think i would approach this questions as a conservation of momentum problem rather than
 
I think i would approach this problem as a conservation of momentum rather than kinetic energy.
Pi = Pf
marvi ar + m apvi ap = marvf ar + m apvf ap

so you know the mass of the apple, both initial and final velocities of the arrow as well as both initial and final velocities of the apple!

Hope that helps!
 
thanks a lot! i was wondering what i was doing wrong lol
 
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