7. A point charge with a mass of 4.8x10-10 kg is moving with a constant velocity of 3.8x105 m/s to the left. It enters a region with an electric field of 6.1x107 N/C to the right, and after it travels 85 cm, has sped up to a velocity of 7.2x105 m/s to the left. a. What was the direction of the force on the charge? How did you determine that? b. Is the point charge positive or negative? How did you determine that? c. What is the magnitude of the charge? [1.73x106 C or 1.73 C]