Preciso da resolução urgente,me ajudem!

O sistema esquematizado ao lado é abandonado em repouso num local em que g= 10 m/s² . O fio e a polia sao ideais e as massas de A e B são respectivamente iguais a 6,0 kg e 8,0 kg. Calcule:
A) o módulo da aceleração de bloco A
B) o módulo da aceleraçao do bloco B
C) a intensidade da tração no fio
D) a intensidade da força exercida pelo fio sobre o eixo da polia

a figura é esta: data:image/jpeg;base64,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


e as respostas são:
A) 10/7 m/s²
B) 10/7 m/s ²
C) 480/7 N
D) 960/7 N

1

Respostas

2014-01-12T12:13:25-02:00
 

A)  Forças que atuam em B , a tensão e o peso B .

forças que atuam em A , mesma coisa.

PesoB - T = massaB. a
T - PesoA = massaA . a

soma

------------------------------------------------

pesoB - peso A = ( massaA + massaB) . a
8.10  -  6.10 = ( 6 + 8) .a
80 - 60 = 14a
20 = 14a

a = 20 / 14  =  10 /7 m/s²


B) Também é a mesma . ( 10 /7 m/s²)

C)  Basta substituir a aceleração em alguma equação

escolher essa ~>

PesoB - T = massaB. a
80 - T = 8 . 10 /7
80 - T = 80 / 7

- T = 80 / 7 - 80
- T =  - 480 / 7  ( - 1) Para eliminar os sinais

T = 480 / 7 N


D)  A intensidade = 2. T

i = 2. 480 /7  =  960 /7 N



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