As you know inertia is an behaviour of matter that objects resist change in their motion. If an object is at rest it will remain at rest and if an object is moving with a constant velocity it will continue to move in that same direction with the same velocity until acted upon by an unbalanced force. Change in motion means acceleration and acceleration takes time. So objects resist change in their motion (acceleration) because they take time to do so and hence have inertia. But what would happen if objects don't take time to accelerate or instaneously accelerate. Would they have inertia even after that? Does this mean time actually causes inertia (or makes feel us so)?