What you need:
A disposable cup (made of styrofoam), A drawing pin, Water, A tub.
What to do:
1. Use the pin to poke two holes on the sides of the cup. The holes should be exactly opposite to each other, about an inch from the cup’s base.
2. Block those holes with your finger and thumb. Then fill the cup with water.
3. Hold the glass over the empty tub. Unplug the holes. What happens? The water leaks out, doesn’t it?
4. Now, cover the holes again. Refill the cup.
5. Hold the cup high above the tub and let it go. Watch the holes carefully.
What happens?
As the cup free-falls into the tub, no water leaks out of the holes! But just as soon as the cup reaches the tub, the water spills from its mouth (obviously) and from the holes. Why?
It’s all gravity! When you first unplugged the holes while holding the cup stationary, water began to leak out and fall down because of gravity. This was the easiest route for the water to move towards the earth that was pulling it.
When you let the cup fall, the cup and the water inside it were falling downwards at the same speed. That’s why the water, instead of spilling outwards, moved down with the cup. Water didn’t need an easier path to get to the earth since it was already doing that inside the cup. Once it reached the tub, it began to flow out once again, trying to go down.
Something similar would happen if you were inside an elevator with its cable cut off. It would be free-falling down and you would be going down with it without actually falling to the elevators floor. That’s because you and the elevator are moving at the same speed. Once you hit the ground, well, that’s another story.
Picture Credit : Google
