A child is sledding. He starts at the top of the hill with a velocity of zero, and 3 seconds later he is speeding down the hill at 12 meters per second. What is the child's acceleration?

Magnitude of acceleration = (change of speed) / (time for the change) =                                             (12 m/s  -  0)   /   (3 sec)  =                                               12/3  =  4 m/s²What's a challenge question ?  Have we all passed the event horizon and been spaghettified without knowing it ?