posted by arcos15 .
An object moves in the +x direction at a speed of 30 m/s. As it passes through the origin, it starts to experience a constant acceleration of 3.7 m/s2 in the -x direction.
(b) How much time elapses before the object returns to the origin?
this is like a projectile problem turned sideways
0 = -(.5 * 3.7 * t^2) + (30 * t)
solve the quadratic for t (you want the non-zero solution)