It should decellerate with -362167 m/s^2.
Basically Delta V/T:
Delta V is 412 - 330
T = =0,084/ ((330+412)/2)
[note: s is the distance, don't know correct figure in english here, v is "delta v" or 82m/s]
I disagree: s = 1/2*a*t²; you have T = 2,264*10^-4s
If you insert that in the above equiation, you get s = 9,28*10^-3m, wich is a little more than 1/10 of the original given 0,084m thickness.
My solution:
s = 1/2*a*t^² (1); and v = a*t (2); (1) in (2) gives you s = 1/2*a*t (3)
=> from (3): t = s / (1/2*v) = 0,084 / (0,5*412-330) = 2,05*10^-3s
=> now in (1)
a = s / (0,5*t²) =
39976 m/s²
check: insert results in (1)
s = 0,5*39976*(2,05*10^-3)² =
0,084m
Skorzeny: I think your mistake is "T = =0,084/ ((330+412)/2)" you are assuming an average velocity of the projectile in the board wich would need a linear decceleration over distance, but it is quadratic. Note: s=1/2*a*t
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