Gather secondary information to predict the value of acceleration due to gravity on other planets.

- The gravitational force on an object is determined by the planet's
**mass**and**"radius"**.- Subsequently the gravitational acceleration ($g$) would also depend on those factors.

- To find the value of $g$ on other planets we would $F = mg$ and $F = \frac{GMm}{r^2}$:

\begin{align} F_g = \frac{GMm}{r^2} \end{align}

But as $F = mg$

(2)\begin{align} mg = \frac{GMm}{r^2} \end{align}

Now remove $m$ from both sides:

(3)\begin{align} g = \frac{GM}{r^2} \end{align}

Where:

- $g$ is the acceleration due to gravity ($ms^{-2}$)
- $G$ is Newton's Universal gravitational Constant. ($6.67 x 10^{-11} Nm^2kg^{-2}$)
- $M$ is the mass of the planet. ($kg$)
- $r$ is the radius of the planet. ($m$)

page revision: 0, last edited: 06 Jan 2011 12:04