1. The problem statement, all variables and given/known data What is the acceleration of a vehicle that changes its velocity from 90 km/h to a dead stop in 13 s? 2. Relevant equations i don't understand how to do this correctly 3. The attempt at a solution i know im supposed to use the formula for acceleration [a= (Vi-Vf)/T] i plugged in 90 for the Vi and 0( the dead stop) for Vf after that i divided by 13 but the answer i got was wrong.