Saturday, February 4, 2012

Hukum Kekekalan Energi Mekanik


aplikasi energi mekan
Hukum kekekalan Enegi Mekanik berbunyi Pada sistem yang terisolasi (hanya bekerja gaya berat dan tidak ada gaya luar yang bekerja) selalu berlaku energi mekanik total sistem konstan. Pada posting tentang macam-macam bentuk energi diantaranya adalah energi potensial dan energi kinetik.

Energi total yang dimaksud pada hukum kekekalan energi mekanik adalah jumlah antara energi potensial dengan energi kinetik.

Energi potensial
Energi potensial adalah energi yang dimiliki benda karena kedudukannya. Energi ini tersembunyi pada benda tetapi bila di beri kesempatan energi ini bisa di manfaatkan contoh misalnya energi potensial pada pegas yang ditarik terjadi juga pada pada karet atau busur panah. Contoh yang kedua adalah Energi potensial gravitasi yaitu energi yang dimiliki benda yang disebabkan oleh ketinggian terhadap suatu titik acuan tertentu.
Besar energi potensial gravitasi sebanding dengan massa, percepatan gravitasi serta ketinggian

Ep = m g h

Keterangan
  • m=massa(kg)
  • g=percepatan gravitasi(m/s2)
  • h=ketinggian(m)
Energi Kinetik
Energi kinetik adalah energi yang dimiliki benda karena geraknya misalnya anak panah yang lepas dari busur memiliki kecepatan dan massa tertentu maka anak panah tersebut memiliki energi kinetik yang besarnya berbanding lurus dengan massa serta kecepatan kuadrat.  Dalam persamaan
Ek = ½ mv2
Keterangan
  • Ek= energi kinetik(Joule)
  • m=massa(kg)
  • v=kecepatan(m/s)
Energi Mekanik
Energi mekanik adalah jumlah total dari energipotensial dengan energi kinetik atau
Em= Ep + Ek
Menurut hukum kekekalan energi mekanik bahwa jumlah energi mekanik selalu tetap dengan syarat tidak ada gaya luar yang bekerja pada sistem.
Em1 =Em2
Ep1 + Ek1 = Ep2 + Ek2
m g h1 + ½ mv12 = m g h2 + ½ mv22
Penerapan hukum kekekalan energi mekanik adalah pada kasus benda jatuh dipermukaan bumi atau berada dalam medan gravitasi bumi. Berhubungan dengan hukum kekekalan energi mekanik dapat disimpulkan.
  1. Pada kedudukan awal, kelajuan sama dengan nol sehingga Ek=0, s atau gerak jatuh bebas.  Sedangkan energi potensial Ep mencapai nilai maksimum, sama dengan energi mekaniknya.
  2. Pada keadaan selanjutnya, energi potensial berkurang dan berubah menjadi energi kinetik. Pada setengah perjalananya, besar energi potensial sama dengan energi kinetik.
  3. Pada saat menyentuh tanah (bidang acuan), seluruh energi potensial berubah menjadi energi kinetik sehingga energi potensialnya Ep=0, sedangkan energi kinetik Ek= mencapai nilai maksimum, sama dengan energi mekaniknya.
Energi potensial, energi kinetik serta energi kinetik merupakan besaran skalar sama halnya dengan usaha oleh karena dimensi serta satuannya juga sama.

Demikian posting yang membahas tentang hukum kekekalan energi mekanik, semoga bermanfaat kurang lebihnya tuliskan di kolom komentar.

19 comments:

  1. Kok aku ngitung gituan mumet lagi ya? Wah ... apa harus balik lagi ke SMA?

    ReplyDelete
    Replies
    1. ga usah balik ke SMA karena tidak akan bisa, waktu hanya berjalan satu arah

      Delete
    2. BAHHHH BACOT LU PERA' CUYY.....!

      Delete
  2. Ini tepat sekali untuk adik saya pak. artikel yang dicari para kebanyakan selajar sekarang.
    mantab

    ReplyDelete
    Replies
    1. ok terima kasih kalau memang diperlukan

      Delete
  3. kalo satuannyo apo dio ye??
    tlong di bales kepepet nih

    ReplyDelete
  4. Mkasih yaa :)
    Bgus nih buat nyelesahin tugas

    ReplyDelete
  5. “Energi tidak dapat diciptakan atau dimusnahkan, energi hanya dapat diubah dari satu bentuk ke bentuk lainnya.” Yang pernah di ucapkan salah seorang ahli fisika Inggris, James Prescott Joule.
    ini saya copas dari blog http://najmialghifary.wordpress.com/2011/11/24/hukum-kekekalan-energi/
    dan ini salah satu contohnya.
    Energi kalor dapat dikonversikan ke energi mekanik, kemudian mekanik bisa menciptakan energi lainnya, semisal energi listrik.nah setelah menjadi energi listrik bisa dikasih contoh berubah lagi menjadi energi apalagi?dan menjadi energi apalagi setelahnya?
    terimakasih sebelumnya :)
    bisa minta tlg di email juga ke dederahmat_rng@yahoo.co.id.

    ReplyDelete
  6. apakah bunyi hukum A kekekalan energi B kekekalan mekanik? jwb sekarang :)

    ReplyDelete
  7. kakk makasih banyak yaa postingan fisikanya bermanfaat sekali untuk tugas, ^^ aku ijin salin buat bahan yaaa makasihhh

    ReplyDelete
  8. waah terimakasih yaa. saya terbantu

    ReplyDelete
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