... redirected Newton to the problem of the "path of a body subjected to a centrally directed force that varies as the inverse square of the distance"; he determined it to be an ellipse, and informed Edmond Halley in August 1684. Halley's interest led Newton to write the Principia. "Book I of the Principia states the foundations of the science of mechanics, developing upon them ... ...

• Word Count: 2460
• Approx Pages: 10
• Grade Level: High School