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Dua buah balok dihubungkan dengan tali dan digantu...

Dua buah balok dihubungkan dengan tali dan digantung pada katrol licin. Katrol dianggap tidak bermassa dan licin. Percepatan gravitasi begin mathsize 14px style 10 space straight m divided by straight s squared end style. Bila massa balok A 1 kg dan balok B 4 kg, hitung percepatan yang dialami balok!

  1. begin mathsize 14px style 1 space straight m divided by straight s squared end style space

  2. begin mathsize 14px style 2 space straight m divided by straight s squared end style 

  3. begin mathsize 14px style 5 space straight m divided by straight s squared end style 

  4. begin mathsize 14px style 6 space straight m divided by straight s squared end style 

  5. begin mathsize 14px style 8 space straight m divided by straight s squared end style 

Jawaban:

Diketahui:

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell m subscript A end cell equals cell 1 space kg end cell row cell m subscript B end cell equals cell 4 space kg end cell row g equals cell 10 space straight m divided by straight s squared end cell end table end style 

Ditanyakan:

Percepatan balok, a = ?

Jawab:

Asumsikan katrol licin sehingga percepatan kedua benda sama. Karena begin mathsize 14px style m subscript B greater than m subscript A end style, balok bergerak ke arah B (balok B turun, balok A naik).

Balok A:

Diagram benda bebas (DBB):

Hukum II Newton arah sumbu Y:

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell sum F subscript y end cell equals cell m subscript A a end cell row cell negative w subscript A plus T end cell equals cell m subscript A a end cell row cell negative left parenthesis 1 right parenthesis left parenthesis 10 right parenthesis plus T end cell equals cell 1 a end cell row cell negative 10 plus T end cell equals a row T equals cell a plus 10 end cell end table end style 

Balok B:

Diagram benda bebas (DBB):

Hukum II Newton arah sumbu Y:

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell sum F subscript y end cell equals cell negative m subscript B a end cell row cell negative w subscript B plus T end cell equals cell negative m subscript B a end cell end table end style 

Substitusi T dari persamaan balok A:

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell negative left parenthesis 4 right parenthesis left parenthesis 10 right parenthesis plus left parenthesis a plus 10 right parenthesis end cell equals cell negative 4 a end cell row cell negative 40 plus a plus 10 end cell equals cell negative 4 a end cell row cell 5 a end cell equals 30 row a equals cell bold 6 bold space bold m bold divided by bold s to the power of bold 2 end cell end table end style 

Dengan demikian, percepatan kedua balok sebesar begin mathsize 14px style 6 space straight m divided by straight s squared end style.

Jadi, jawaban yang benar adalah D.

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