1. The problem statement, all variables and given/known data Dave walks to the left and then turns around and walks to the right without pausing. At the exact moment that he turns around is a. velocity & acceleration zero b. velocity zero & acceleration non -zero c. velocity non-zero, acceleration zero d. velocity and acceleration non-zero e. all of the above depending on the situation 2. Relevant equations 3. The attempt at a solution I think his velocity is non-zero because he's still walking while his acceleration is zero because his velocity is still constant? Also, if a particle has a constant position it has a non-zero velocity? (because it has to be changing) I believe you have a non-zero velocity when the acceleration slope is zero and when an object falls near the surface of the Earth.