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26. We choose +
y
upward, which implies
a
> 0 (the acceleration is upward since it
represents a deceleration of his downward motion through the snow).
(a) The maximum deceleration
a
max
of the paratrooper (of mass
m
and initial speed
v
= 56
m/s) is found from Newton’s second law
Fm
g
m
a
snow
max
−=
where we require
F
snow
= 1.2
×
10
5
N. Using Eq. 215
v
2
= 2
a
max
d
, we find the minimum
depth of snow for the man to survive:
()
2
22
5
max
snow
85kg 56m s
1.1 m.
2 1.2 10 N
vm
v
d
aF
m
g
==
≈
=
−
×
(b) His short trip through the snow involves a change in momentum
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This note was uploaded on 05/17/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.
 Spring '08
 Any
 Physics, Acceleration, Mass

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