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fisica1-youn-e-freedman-exercicios-resolvidos

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9.15: From Eq. (9.11),<br />

ω<br />

2<br />

θ − θ0<br />

0 z<br />

=<br />

=<br />

t<br />

αzt<br />

60.0rad (2.25rad s )(4.00s)<br />

− = −<br />

2 4.00s<br />

2<br />

10.5rad<br />

s.<br />

2<br />

0z<br />

0<br />

z t 6.00 s<br />

s<br />

av<br />

= (70rad s)(6.00s) = 420rad.<br />

z<br />

ωz<br />

140 rad s<br />

9.16: From Eq. (9.7), with ω = , α = = = 23.33rad .<br />

easily found from θ = ω t −<br />

The angle is most<br />

9.17: From Eq. (9.12), with ωz<br />

= 0,<br />

the number of revolutions is proportional to the<br />

square of the initial angular velocity, so tripling the initial angular velocity increases the<br />

number of revolutions by 9, to 9.0 rev.

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