Acceleration occurs when an object speeds up.

Positive acceleration occurs when an object speeds up.

Explanation:

Acceleration is the rate of change in velocity per unit time:

where is the change in velocity while is the time interval. From the formula, we can understand that when is positive, so when the object is speeding up, the acceleration is positive; on the contrary, when is negative (so, when the object is slowing down), the acceleration is negative.

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