Equations · Physics
Newton's law of universal gravitation
Every two masses attract with a force proportional to both masses and falling with the square of the distance.
F = G m₁m₂ / r²
Aethel says
F equals G m sub one m sub two over r squared
What it says
Double either mass and the pull doubles; double the distance and it falls to a quarter. The same law holds an apple to the Earth and the Moon in its orbit.
Symbol by symbol
| Symbol | Say it | Means |
|---|---|---|
| G | G | the gravitational constant, about 6.674 × 10⁻¹¹ N·m²/kg² |
| m₁, m₂ | m sub one, m sub two | the two masses |
| r | r | the distance between their centres |
Where you meet it
Mechanics, astronomy and orbital dynamics.
Questions
How do you say Newton's law of universal gravitation out loud?
F = G m₁m₂ / r² is read: “F equals G m sub one m sub two over r squared.” That is exactly what Aethel says when it meets the formula in a book.
What does G mean in Newton's law of universal gravitation?
G (said “G”) is the gravitational constant, about 6.674 × 10⁻¹¹ N·m²/kg².
What does m₁, m₂ mean in Newton's law of universal gravitation?
m₁, m₂ (said “m sub one, m sub two”) is the two masses.
Can I listen to the equations in my own textbook like this?
Yes. Upload a PDF, EPUB or text file and Aethel reads it aloud with every equation spoken as maths, the way it reads this one, and highlights each sentence as it goes. You can start free.