According to second law, F = ma
If F = 0, a = 0 since m ≠ 0,
But a = {v – u \over t}
or, v – u = 0 so, v = u for whatever time t is taken.
This means that the object will continue moving with uniform velocity, u throughout the time, t. If u is zero then v will also be zero. That is, the object will remain at rest.