When a positively charged object moves in the same direction as the electric field, the electric potential energy of the object a. becomes zero b. increases c. decreases d. stays the same. me asap. i really appreciate it!

The answer is C.

Because if the object that has been or is positively charged moves in the same direction as the electric field the electric potential energy of the object would obviously decrease.

The  field does negative work on so the potential energy decreases.  

what was the acceleration of the 2 kg cart?

⇒ 16.0 cm/s2

what was the acceleration of the 4 kg cart?

⇒ 8.1 cm/s2

what was the acceleration of the 6 kg cart?

⇒ 5.3 cm/s2