Q. A circular arc has a uniform linear charge density of -7 nC/m. The value of the Coulomb constant is 8.98755 * 10^9 N*m^2/ C^2. What is the magnitude of the electric field at the center of the circle along which the arc lies? The radius of the arc is 2.5 m and it goes 243 degrees around the center, starting at the positive x axis.
Q. A stationary radar operator determines that a ship is 17 km south of him. An hour later the same ship is 21 km southeast. If the ship moved at constant speed and always in the same direction, what was its velocity during this time? (Hint: Take the origin to be the location of the radar.)