The electric field inside a uniformly charged sphere with positive charge q and radius r points radially outward from the center of the sphere and has magnitude e=qr/4πϵ0r3 at a distance r from the center. by integrating the electric field, find the potential difference between the center of the sphere and its surface.

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?