This experiment is about " cart on a ramp". we slowly moved the cart from the bottom of the ramp to the top with our hands about 15 cm away from the motion detector and we let it rolled back down by itself. that's all i have about the question. i don't know how to answer it.

in a free rolling part of motion ( cart on a ramp) there is a moment when velocity is 0m/s. what happenwith the position at that point? what happening with acceleration at that point? explain below, including information about mathematical relationship.