Free App
https://play.google.com/store/apps/details?id=com.ionicframework.gravity11app440505
Pro App
https://play.google.com/store/apps/details?id=com.ionicframework.gravity11pro329364

About
an open source physics at Singapore simulation based on codes written by Andrew Duffy and Loo Kang WEE.
more resources can be found here
http://iwant2study.org/ospsg/index.php/interactive-resources/physics/02-newtonian-mechanics/08-gravity

Introduction
Every object sets up a gravitational field around itself due to its mass. When two objects enter each other’s gravitational fields, they will be attracted towards each other.
Hence, a gravitational field is a region of space in which any object that lies in it experiences a gravitational force towards the object that creates the field, due to its mass.
This Lab allows the inquiry of gravity concepts of field and potential for a two mass setup.


Interesting Fact
This app produce real numbers to coincident with the real world data.

Acknowledgement
My sincere gratitude for the tireless contributions of Francisco Esquembre, Fu-Kwun Hwang, Wolfgang Christian, Félix Jesús Garcia Clemente, Anne Cox, Andrew Duffy, Todd Timberlake and many more in the Open Source Physics community. I have designed much of the above based on their ideas and insights.
This research is supported by the eduLab project NRF2015-EDU001-EL021 , awarded by the Prime Minister Office, National Research Foundation (NRF), Singapore in collaboration with National Institute of Education (NIE), Singapore and the Ministry of Education (MOE), Singapore.
reference:
http://edulab.moe.edu.sg/edulab-programmes/existing-projects/nrf2015-edu001-el021

Network Learn together?
FaceBook Fan Page: https://www.facebook.com/Open-Source-Physics-Easy-Java-Simulation-Tracker-132622246810575/
Twitter: https://twitter.com/lookang
YouTube: https://www.youtube.com/user/lookang/videos
Blog: http://weelookang.blogspot.sg/
Digital Library: http://iwant2study.org/ospsg/