How can the heavy object land at the same time as the lightweight object?

Like, if you were to drop a thick, hard-cover dictionary and a empty water bottle at the same time, how do they land at the same time?? Wouldn't the heavier object land first????How can the heavy object land at the same time as the lightweight object?
The acceleration of gravity is NOT always constant. It differs from altitude ( distance from center of earth ) and position. It is only roughly 9.8 meters/sec^2 on average. Neglecting air resistance, the force of the atmosphere beneath the falling object that inhibits acceleration, two objects of dissimilar masses will fall at the same rate. Rate and velocity are not the same. While velocity is a rate, rates can be anything from speed to acceleration to decay processes. The derivitive of distance with respect to time is calculus base velocity which does not come in to play in the horizontal axis of our thought experiment. Only forces in the vertical plane can effect the time is takes for the object to reach the ground.How can the heavy object land at the same time as the lightweight object?
Air resistance does play a factor, so obviously if you drop a feather and a brick at the same time, both are not going to land at the same time. This is because the ratio of their surface area to their mass is different. But if you neglect air resistance, then everything falls at an equal acceleration on Earth (approximately 9.8 m/s^2).
a = F/m, but F = weight = m*g


substituting,





a = m*g/m = g; The m's cancel, so a is not a function of m, only g.





All this assumes no air resistance. When this factor is included, objects with a greater density will have a greater acceleration and reach a higher terminal velocity than their less dense counter parts.
gravity, the force that accelerates these objects is constant for both, around 9.8 meters per second squared. So assuming they leave your hand (or whatever you were holding them with) at the same speed they drop at the same time