fisica1-youn-e-freedman-exercicios-resolvidos

10.40: The skater’s initial moment of inertia is
2 1
I = (0.400 kg ⋅ m ) + (8.00 kg)(1.80 m)
2
and her final moment of inertia is
Then from Eq. (10.33),
= 2.56 kg
2
1
⋅
I
2
= (0.400 kg ⋅ m ) + (8.00 kg)(25×
10
m) = 0.9 kg
−2
2
⋅
m
m
2
2
,
.
ω
I
2.56 kg ⋅ m
0.40 rev s)
0.9 kg ⋅ m
2
1
2
= ω1
= (
I2
2
=
1.14 rev
s.
Note that conversion from rev/s to
rad s is not necessary.
2
2
10.41: If she had tucked, she would have made (2)(3.6 kg ⋅ m ) 18 kg ⋅ m ) = 0. 40 rev in
the last 1.0 s, so she would have made ( 0.40 rev)(1.5 1.0) = 0. 60 rev in the total 1.5 s.
10.42: Let
I
I
1
2
= I
0
= I
0
= 1200kg ⋅ m
+ mR
Then, from Eq. (10.33),
2
2
= 1200kg ⋅ m
,
2
+ (40.0kg)(2.00 m)
2
= 1360kg ⋅ m
2
.
ω
I ⎛ 2π
rad ⎞1200 kg.m
= ⎜ ⎟
⎝ 6.00 s ⎠1360 kg.m
2
1
2
= ω1
=
2
I2
0.924rad
s.