More about PhET
You can get the 1.0 version of PhET 697.89 MB from this website. The software developer is University of Colorado who provides it free of charge. Belonging to the Education category, namely Science, makes it popular among such programs. This program is officialy supported on Windows XP/Vista/7/8/8.1/10 operating systems. The antivirus check of the direct download link proved it to be safe.