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Perhatikan tabel berikut! Balok Massa Percepatan Waktu A 8 kg 2 m/ 2 s B 10 kg 1 m/ 4 s Jika kedua balok mula-mula diam, perbandingan usaha kedua benda adalah...

Pertanyaan

Perhatikan tabel berikut!

Balok Massa Percepatan Waktu
A 8 kg 2 m/begin mathsize 14px style straight s squared end style 2 s
B 10 kg 1 m/begin mathsize 14px style straight s squared end style 4 s

Jika kedua balok mula-mula diam, perbandingan usaha kedua benda adalah...

  1. 1 : 2space 

  2. 2 : 1undefined 

  3. 3 : 4undefined 

  4. 4 : 5undefined 

  5. 5 : 4undefined 

Pembahasan Soal:

Diketahui:

begin mathsize 14px style m subscript A equals 8 space kg m subscript B equals 10 space kg a subscript A equals 2 space straight m divided by straight s squared a subscript B equals 1 space straight m divided by straight s squared t subscript A equals 2 space straight s t subscript B equals 4 space straight s v subscript 0 equals 0 space straight m divided by straight s space left parenthesis karena space benda space mula minus mula space diam right parenthesis E subscript k A subscript 0 end subscript equals E subscript k B subscript 0 end subscript equals 0 space straight J space left parenthesis karena space benda space mula minus mula space diam right parenthesis end style  

Ditanya: begin mathsize 14px style W subscript A space colon space W subscript B end style ?

Penyelesaian:

Kita hitung kecepatan masing-masing benda

begin mathsize 14px style v subscript A equals v subscript 0 plus a subscript A t subscript A v subscript A equals 0 plus 2 cross times 2 v subscript A equals 4 space straight m divided by straight s  v subscript B equals v subscript 0 plus a subscript B t subscript B v subscript B equals 0 plus 1 cross times 4 v subscript B equals 4 space straight m divided by straight s end style 

Setelah mendapatkan besarnya kecepatan masing-masing benda, kita bisa membandingkan usaha kedua benda dengan mencari perubahan energi mekaniknya

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row blank blank cell W subscript A over W subscript B end cell end table table attributes columnalign right center left columnspacing 0px end attributes row blank equals blank end table table attributes columnalign right center left columnspacing 0px end attributes row blank blank cell fraction numerator increment E subscript k A end subscript over denominator increment E subscript k B end subscript end fraction end cell end table end style
Yuk kita hitung...
begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell W subscript A over W subscript B end cell equals cell fraction numerator E subscript k A end subscript minus E subscript k A subscript 0 end subscript over denominator E subscript k B end subscript minus E subscript k B subscript 0 end subscript end fraction end cell row cell W subscript A over W subscript B end cell equals cell fraction numerator bevelled 1 half m subscript A v subscript A squared minus 0 over denominator bevelled 1 half m subscript B v subscript B squared minus 0 end fraction end cell row cell W subscript A over W subscript B end cell equals cell fraction numerator bevelled 1 half cross times 8 cross times 4 squared space straight J over denominator bevelled 1 half cross times 10 cross times 4 squared space straight J end fraction end cell row cell W subscript A over W subscript B end cell equals cell fraction numerator 64 space straight J over denominator 80 space straight J end fraction end cell row cell W subscript A over W subscript B end cell equals cell 4 over 5 end cell end table end style  

Jadi, perbandingan usaha kedua benda adalah 4 : 5. (D)undefined 

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 19 Mei 2021

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