Energi Potensial
| English | Bahasa Indonesia |
|---|---|
| potential energy/pəˈtenʃl ˈenədʒi/ | energi potensial |
A raised hammer holds energy, waiting
- Lift a hammer above a nail and it just... waits. Yet it now holds energy, ready to strike.
- Energy can be stored by position or shape, not only by motion.
- We call this stored energy potential energy 势能.
- Release it and the store pours back out as motion.
Gravitational potential energy
- Lifting a mass $m$ to a height $h$ stores gravitational PE: $E_p = mgh$.
- It equals the work done against gravity to raise it.
- The higher you lift, or the heavier the mass, the more energy is stored.
- Let it fall and this $mgh$ converts into kinetic energy.
Simpan energi dengan mengangkat
Tingkatkan ketinggian awal dan lihat berapa banyak energi potensial yang tersimpan, siap berubah menjadi energi kinetik.
Angkat buku $2\ \text{kg}$ ke rak setinggi $1.5\ \text{m}$ ($g = 9.8\ \tfrac{\text{N}}{\text{kg}}$). Berapa banyak energi potensial gravitasi yang tersimpan, dalam joule?
$E_p = mgh = 2 \times 9.8 \times 1.5 = 29.4\ \text{J}$.
Energi potensial gravitasi $mgh$ meningkat ketika Anda meningkatkan salah satu dari ini?
$E_p = mgh$ bertambah seiring massa, ketinggian, dan $g$. Warna tidak relevan.
Ketika benda terangkat jatuh, energi potensial gravitasinya berubah menjadi energi kinetik.
Saat ketinggian turun, $mgh$ menurun dan PE yang hilang muncul kembali sebagai energi kinetik $\tfrac12 mv^2$.
Elastic potential energy
- A stretched or compressed spring also stores energy: elastic PE $E_p = \tfrac12 k x^2$.
- Here $k$ is the spring constant and $x$ the extension.
- A drawn bow, a wound spring, a squeezed trampoline — all hold elastic PE.
- Release the deformation and the store becomes motion.
Energi potensial elastis pegas adalah $\tfrac12 k \_\_$ (lengkapi bagian yang hilang).
$E_p = \tfrac12 k x^2$ — ia bertambah sesuai kuadrat pertambahannya.
Potential energy is relative
- Gravitational PE depends on the reference level you choose for $h = 0$.
- Only changes in PE ($\Delta E_p$) matter physically, so you may pick any zero.
- PE goes with conservative forces — gravity and springs — whose stored energy is fully recoverable.
- Friction is not conservative: its energy turns to heat and cannot be recovered as PE.
Energi potensial gravitasi memiliki satu nilai absolut, sama untuk setiap pengamat.
Nilai ini diukur relatif terhadap tinggi nol yang dipilih; hanya perubahan PE yang bermakna secara fisik.
Energi tersimpan dari gaya manakah yang dapat dipulihkan sepenuhnya sebagai energi potensial?
Gravitasi adalah gaya konservatif — energinya dapat dipulihkan sepenuhnya. Gesekan mengubah energi menjadi panas.
Gravitational PE is measured relative to a chosen zero height — there is no absolute value. Always state where $h = 0$ is (the floor, the ground, the table). Only the change in PE affects the physics.
Lift a $2\ \text{kg}$ book to a shelf $1.5\ \text{m}$ high ($g = 9.8\ \tfrac{\text{N}}{\text{kg}}$).
- $E_p = mgh = 2 \times 9.8 \times 1.5 = 29.4\ \text{J}$.
That $29.4\ \text{J}$ is stored, ready to become kinetic energy if the book falls.
Potential energy is stored energy of position or shape. Gravitational PE is $E_p = mgh$; elastic PE is $E_p = \tfrac12 kx^2$. Gravitational PE is measured relative to a chosen zero, and only its change matters. It comes from conservative forces.