elementary angular-momentum with force of gravity// angular-momentum equals electric field// physics series for high school, book 8 (english edition)  last revision was 15mar2021. this is ap's 62nd published book of science. <br> <br>-------------------------- <br>table of contents <br>-------------------------- <br> <br>1) angular momentum is one of the most difficult concepts of physics. <br> <br>2) strange motion of uranus and its satellites. <br> <br>3) units of physics <br> <br>4) linear momentum <br> <br>5) angular momentum <br> <br>6) principle that angular momentum is represented by an ellipse. <br> <br>7) principle of gravity <br> <br>8) return and review of the moons (satellites) of uranus. <br> <br>9) quantum duality that is electricity to magnetism, and that is angular momentum with force of gravity. <br> <br>10) angular-momentum equals electric-field. <br> <br>11) angular-momentum equals electric-field equals area speed (area velocity).