GEOG 2P07 Lecture : Lecture # 4 - Representing the Earth on Map (Pt.2) & Intro to Remote Sensing

Three charges,
q1 = +2.08 10-9 C, q2 = -3.06 10-9 C, and q3 = +1.11 10-9 C,
are located on the x-axis at x1 = 0, x2 = 10.0 cm, and x3 = 20.0cm.
Find the resultant force on q3.
magnitude

At 9:30 AM, Alexandra is yards away from class and is walking miles per hour towards class. Also at 9:30 AM, Sam is walking towards a class at miles per hour from some unknown distance. They arrive at class at exactly the same time. How many seconds after 9:30 AM did they arrive at class and how far away was Sam from class at 9:30 AM?