How does increasing the
speed of an object change its
momentum?

When you increase speed, you add energy and increase momentum as it would require more energy to change, stop or reverse the object's direction of travel than before the speed increase. Increasing the speed increases the momentum proportionally.

Explanation:

When you increase the velocity of an object, you increase its momentum

Explanation:

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