Supiyanto Kelas X Evaluasi Bab 3 Nomor 13

Suatu titik melakukan gerak melingkar beraturan sehingga tiap menit membuat 300 putaran. Jika jari-jari lintasan 4 cm, percepatan sentripetal adalah …

A. 4{{\pi }^{2}}~m.{{s}^{-2}} D. 4000{{\pi }^{2}}~m.{{s}^{-2}}
B. 40{{\pi }^{2}}~m.{{s}^{-2}} E. 144000{{\pi }^{2}}~m.{{s}^{-2}}
C. 400{{\pi }^{2}}~m.{{s}^{-2}}

Penyelesaian

Kecepatan sudut dalam radian

\text{ }\!\!\omega\!\!\text{ }=300\frac{\text{rotasi}}{\text{menit}}=300\times \frac{2\text{ }\!\!\pi\!\!\text{  }\!\!~\!\!\text{ rad}}{60\text{ }\!\!~\!\!\text{ detik}}=10\text{ }\!\!\pi\!\!\text{  }\!\!~\!\!\text{ rad}/\text{s}

 

Percepatan sentripetal

{{\text{a}}_{\text{s}}}=\frac{{{\text{v}}^{2}}}{\text{R}}=\frac{{{\left( \text{ }\!\!\omega\!\!\text{ R} \right)}^{2}}}{\text{R}}={{\text{ }\!\!\omega\!\!\text{ }}^{2}}\text{R}={{\left( 10\text{ }\!\!\pi\!\!\text{ } \right)}^{2}}\times 4\times {{10}^{-2}}=4{{\text{ }\!\!\pi\!\!\text{ }}^{2}}\text{ }\!\!~\!\!\text{ m}/{{\text{s}}^{2}}

 

Jawaban A

Supiyanto. 2006. FISIKA UNTUK SMA KELAS X. Jakarta: Phiβeta.

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