Suppose a strong electromagnet is attracting a metal object and accelerating it towards the magnet. Suddenly, the power to the magnet is shut off. I presume that the object continues to accelerate for a very very brief period before moving at constant speed, because the electromagnetic wave can only travel at light speed, and thus, the influence of the magnet on the object cannot be instantaneous. Now maybe the definition of simultaneity makes this assumption invalid, but my real question is, supposing I reword the question to read 'a strong gravity field is attracting the object, and suddenly, the gravity field is shut off...". Are the results of its influence on the object the same as the electromagnetic force, in terms of the time delay of its influence on the object?