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  • #: 14202
  • Price: $2.99 In Apple Store
  • Category: Education
  • Updated: 2013-04-02
  • Current Version: 2.10
  • 2.10
  • Size: 6.80 MB
  • Language: English
  • Seller: Oriol Ferrer Mesia
  • Requirements: Compatible with iPhone, iPod touch, and iPad. Requires iOS 3.0 or later
  • © Oriol Ferrer Mesia 2010
  •  Add to Favorite apps



G is a Gravitation simulator designed for iPad / iPhone.

Check the demo video at http://www.gravityApp.info

G allows you to quickly experiment the effects of the Universal Gravitation by adding bodies into a simulation, seeing how they react to each other in real time, all in a true multitouch environment. G offers a vast universe to add your bodies into, potentially allowing you to create stable planetary systems, binary star systems, and other multiple-body complex systems.

G is very simple to use. When you first start it, you are presented with the solar system. The Sun and all planets from Mercury to Uranus are added to the simulation, including the Earth's Moon.

First, get familiar with how to navigate G's Universe.

- Drag on empty space to pan around the universe

- Pinch (two fingers) to zoom in and out the Universe.

- Tap on a body to select it, making the camera follow it.

You can then start interacting with the system, by adding new bodies, modifying or deleting the existing ones.

- Double-tap on empty space to create a body.

- Drag after double- tap to set the new body's initial velocity.

- Drag an existing body to relocate it.

- Double-tap on an existing body to set a new velocity.

The placement, the mass and the initial velocity of the newly added bodies will dictate how "successful" your system will be. Bodies in G will collide when in contact, so if one of your bodies hits another one, they will merge into a single body, creating debris in the process.

Want to see what would happen if our Sun suddenly disappeared? Just delete it from the simulation, and watch all the Solar System planets react to the change... What would happen if the sun decreased it's mass? Go ahead and try it, it's not pretty.

G provides a settings screen that allows to toggle various visual aids, (universe grid, body trails, etc), as well as the simulation speed.

G allows you to store your systems to get back to them later. Up to 7 systems can be stored simultaneously, and loaded anytime. A screenshot of the system is also stored together with the date it was stored in. G also provides a few presets, including the Solar System, and a few other particular systems. You can also import/export your systems from/to any other app (Dropbox, for example) or email.

The physics implemented in G follow "Newton's Laws of Universal Gravitation", which states that every massive particle in the universe attracts every other massive particle with a force which is proportional to the product of their masses and inversely proportional to the square of the distance between them.

In case you are curious about Newton's Laws of Universal Gravitation, G provides a quick view of the Wikipedia's definition of such laws.

What's New in Version 2.10

Lots of new features!

True multitouch interface; pan & zoom while creating / moving, perform multiple actions at once.
Improved zoom
New body editor allows numerical data input
New body cloning tool
In-place dynamic mini-UI
File export, share your system by email, dropbox, etc.
User action panels, indicate which action each finger is doing + numerical data.
New adaptive space grid, covers all user space, less intrusive
User selectable simulation precision
Body collisions now produce space debris
Improved body looks, LOD textures
New compass, always points to system's origin coordinates (0,0) when not on screen
Orbit previews when editing the system
Realtime gravitational field preview when editing the system
Improved looks on prediction path
User Interface overhaul, left and right handed ready, customized native UI elements
Sound effects
Proper retina support
New factory presets, including "Binary Star", "Spirograph" and others
App analytics, can be disabled by the user
Countless small tweaks to make the app great

iPhone Screenshots

G iPhone Screenshot 1
G iPhone Screenshot 2
G iPhone Screenshot 3
G iPhone Screenshot 4
G iPhone Screenshot 5

Video Reviews

No video review.

Customer reviews

Write a Review

Rated 4/5 based on 3 customer reviews.


4/5 stars

Good, but needs ability to be precise.

This game provided me with countless hours of entertainment, and still is. However, there are 4 edits that I feel this app needs in order to deserve 5 stars.

1: there should be a way to select an exact mass for a body, preferably by typing it in.
2: there should be a way to select a precise velocity for a body, preferably by typing it in.
3: There should be options for simulation speeds of 5, 10, 50, 100, and 500. There are times I want the simulation to run slower than 1000 but I certainly don'y want it to run at a measly 1x speed!
4: there should be a way to shift a body's position without changing its velocity. This way, if an object such as a star begins to shift and I don't want it to, I can fix the problem.
Other things i recommend are the option to zoom in more and shift the grid background to a new location.

4/5 stars

Good, but....

Good but could be better, an option to create a preset planet a proper star, asteroid belt, etc. Would be nice if an option to plot an entire orbit was added and most hopefully a possibility of a black hole addition were to be added.

4/5 stars

Camera Issues

While "G" is an amazing app, there needs to be some fixes with the camera. It is very easy to quickly get into the middle of nowhere, with no idea how to get back. There are a few ways to fix this issue, preferably all of them bieng implemented.
1. An arrow pointing towards the center of the graph (this would be able to be turned on and off)
2. A "camera reset" button that would set the camera in the middle of the graph and at standard zoom
3. When you enter a new simulation, have the camera automatically set in the center and at standard zoom


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