Fun With Falling
Objects
Falling Objects
Becomes Weightless
Do you know that falling objects have no weight?
When we see a stone, an apple, or a person fall, it seems obvious that gravity is pulling the object downward. Yet physics reveals a surprising truth: during free fall, the object is weightless. This idea is one of the deepest insights in modern science because it connects everyday experience with the theory of gravity and even helps explain why astronauts float in orbit.
Weight And Free Fall
First of all, what is weight? In ordinary language, weight means how heavy something feels when it presses on a support such as the ground, a chair, or a scale. If you stand on a scale, the scale pushes up on you, and you push down on it. That supporting force is what produces the sensation of weight.
But when an object is falling freely, there is no support acting on it. Remember, gravity is still acting, but nothing is resisting the fall. As a result, the object does not feel its own weight. In this sense, a falling object is weightless.
Falling Water Bottle
With Holes In It
Please watch the video of falling water bottle with holes in it. You may notice that as long as the bottle is held, water keeps spurting out of all the holes. But the moment the bottle is dropped, water stops flowing out of the holes. Why?
First, we need to see why water flows out of holes when it is not falling. See the picture below. Because of the weight of the water column the pressure inside the bottle P2 is greater than P1, the air pressure outside the bottle at that point. Hence water spontaneously starts spurting out of the hole because of the pressure difference.
However, when the bottle is dropped the water column inside the bottle becomes weightless. The pressure-gradience vanishes. In fact, P1 becomes slightly greater than P2. Hence, the greater air pressure outside of the hole is able to hold the water inside. Consequently, the flow of water stops as the bottle is falling.
Falling Spring Balance
With a Weight Hanging
Please take look at the video of falling spring balance with 100 grams of weight hanging from it.
You can notice that the spring balance shows 100 when it is held. The moment we drop it the reading springs back to zero. Why? There is no normal force acting on the weight. Hence it becomes weightless.
Conclusion
These experiments prove an important point: a falling object becomes weightless.
Weightlessness does not mean that gravity has vanished; instead, it means that the support forces that normally make the weight noticeable are absent. This profound idea, sharpened by Einstein into the equivalence principle, transformed our understanding of gravity and remains one of the cornerstones of modern physics.