Physics for Kids is described as 'This app brings basic Physics concepts and facts for Kids, Motion, Light, Energy, Electricity and much more. Learn the concepts with you kids in a fun way. Includes Experiments which the kids can do at home or at school to learn basic physics principles' and is an app in the Education & Reference category. There are five alternatives to Physics for Kids for Online / Web-based, Android and iPhone. The best alternative is PhET Interactive Simulations, which is both free and Open Source. Other great apps like Physics for Kids are EMANIM Online (Free), LabsLand (Paid), Amanogawa.com (Free) and myPhysicsLab (Free, Open Source).
EMANIM is a web app displaying interactive animations of electromagnetic waves and presenting phenomena such as polarization, superposition, interference, absorption, refraction, and optical activity (linear and circular dichroism and birefringence).
LabsLand lets students access real educational laboratories through the Internet. Schools, institutions and homeschoolers can use it to provide real labs and real practical and scientific education without having the physical equipment themselves.
The myPhysicsLab website shows the simulations running and contains explanations of the math behind them. There are around 50 different simulations in the source code, each of which has has an example file which is mainly for development and testing.