fisica1-youn-e-freedman-exercicios-resolvidos

5.101: a) The rock is released from rest, and so there is initially no resistive force and
2
a = (18.0 N) (3.00 kg) 6.00 m s .
0
=
2
b) (18.0 N − (2.20 N ⋅ s m) (3.00 m s)) (3.00 kg) = 3.80 m s . c) The net force must be
1.80 N, so kv = 16.2 N and v = ( 16.2 N) (2.20 N ⋅ s m) = 7.36 m s.
d) When the net
force is equal to zero, and hence the acceleration is zero, kv
t
= 18.0 N and
v = (18.0 N) (2.20 N ⋅ s m) 8.18 m s. e) From Eq. (5.12),
t
=
⎡ 3.00 kg
y = (8.18 m s) ⎢(2.00 s) −
(1 − e
⎣ 2.20 N ⋅s
m
= + 7.78 m.
From Eq. (5.10),
−((2.2 N⋅
s m)
v = (8.18 m s)[1−
e
= 6.29 m s.
From Eq. (5.11), but with a
0
instead of g,
2 −((2.20 N⋅s
m)
a = (6.00 m s ) e
.
f)
v
1−
= 0.1 = e
v
t
(3.00 kg))(2.00 s)
−(
k m)
t
m
t = ln (10) = 3.14 s.
k
,
−((2.20 N⋅s
m) (3.00 kg))(2.00 s)
(3.00 kg))(2.00 s)
so
]
= 1.38 m s
2
.
⎤
) ⎥
⎦