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Física<br />

a) Faça um diagrama indicando as forças que atuam sobre uma das massas m.<br />

b) Calcule a velocida<strong>de</strong> angular Ω para a qual θ = 30°.<br />

a)<br />

T cos θ<br />

T<br />

T cos θ<br />

T<br />

θ<br />

T sen θ<br />

T sen θ<br />

mg<br />

mg<br />

mg<br />

(2 pontos)<br />

Resposta<br />

esperada<br />

b)<br />

∑F y 0⇒<br />

Tcosθ<br />

= =<br />

mg<br />

∑<br />

F c<br />

= mω 2 r ⇒ Tsenθ = mω 2 ( d + Lsenθ)<br />

tg30° = mω 2 ( d+<br />

L⁄<br />

2)<br />

-------------------------------------<br />

mg<br />

g⋅<br />

tg30° 10x1,8<br />

ω = ----------------------- = ------------------ = 30rad/s = 5,<br />

5rad/s<br />

d+<br />

L⁄<br />

2 3x0,2<br />

(3 pontos)<br />

Exemplo<br />

acima da<br />

média<br />

Exemplo<br />

abaixo da<br />

média<br />

126

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