A student wishes to conduct an experiment to measure the strength of the electric field created by a piece of carpet with a static electric charge at an arbitrary distance away from the carpet. The student tacks the carpet piece to a wall and then rubs a balloon on her head to give it a charge. She releases the balloon at the same height as the carpet and a certain horizontal distance in front of it.
Using a motion detector, the student determines the initial horizontal acceleration of the balloon. She repeats this process with several different balloons, releasing each from the same location.
Which pair of additional measurements would allow the student to calculate the strength of the electric field at the location of interest?