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37. (a) Since
τ
=
dL
/
dt
, the average torque acting during any interval
Δ
t
is given by
τ
avg
=−
LL
t
fi
di
Δ
, where
L
i
is the initial angular momentum and
L
f
is the final angular
momentum. Thus,
22
avg
0.800 kg m s 3.00 kg m s
1.47 N m
1.50s
⋅−
⋅
==
−
⋅
,
or
avg

 1.47 N m
=⋅
. In this case the negative sign indicates that the direction of the
torque is opposite the direction of the initial angular momentum, implicitly taken to be
positive.
(b) The angle turned is
2
0
/2.
tt
θω α
=+
If the angular acceleration
α
is uniform, then so
is the torque and
=
τ
/
I
. Furthermore,
ω
0
=
L
i
/
I
, and we obtain
()
(
)
2
2
2
2
3.00kg m s 1.50s
1.467 N m 1.50s
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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, Angular Momentum, Momentum

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