Parachutes have a hole in the top to provide a smoother and more controlled ride. Without the hole the only place air has to go is around the edges of the parachute. When the chute tilts a lot of air spill out the high side, which is destabilizing. The hole lets air pass through, so there is always a flow into and through the chute, so it's not trying to spill out the bottom.
The manipulated variable in this experiment would be the size of the parachutes. By changing the size of the parachutes, the scientist can observe how it affects the time it takes for the parachutes to fall to the ground.
A parachute works by trapping air underneath, but when the air is trapped the pressure increases and some of the air has to escape. If there were no hole in the center of a round parachute, such as the military 'chutes used in WW2, the excess air would have nowhere to escape except under the edges of the 'chute, which would cause increasingly violent oscillation and quickly the collapse of the 'chute, which would drop the parachutist to the ground at high speed and kill him. The central hole allows a controlled release of the air pressure in the 'chute, preventing oscillation and the collapse of the 'chute.
The variable being studied is the size of the parachutes.
If you have two parachutes, one big and one small, the biggest one will take more time then the other parachute. This happens because there is more room in the parachute which is causing air to go in side, which is air resistance. The smaller parachute has a lot of air resistance because it is smaller and there is less room for the air to go inside. However, the bigger balloon has little air resistance because it has more room in it for the air to get inside. The air is pushing the balloon up so it will fall slower.
To keep the pressure equalized. If you have a pen with no hole, and were to take it up in an airplane, or even to the top of a building, the pressure difference could cause the ink to flow out of the pen creating a mess and making writing really messy. There is a hole in the body of the Compressed polystyrene to equalise atmospheric pressure, for the reasons stated above, however the hole in the top of the lid is to prevent children for sucking the lid into their throat, subsequently this provides an air passage in such a case.
Parachutes are designed to catch the air therefore slowing you down on impact. If there happened to be a hole, the air passes through it, making your impact to the ground faster.
Prim and many other kids are taken to the capitol and parachutes fly down on top of them. They all think it is a gift, but it was Gale and Beetee's bomb idea. The parachutes were bombs and they killed Prim.
Its still parachutes.
Modern parachutes are made of panels of what is known as ripstop nylon. There is no 'top' so to speak.
Parachutes come in varying sizes.
It is called a blow hole.
The small hole is for headphones.
A is the first two holes on the top covered and the bottom hole covered. B is the first hole on the top and on the bottom. C is the second hole ( not the first hole ) and the bottom hole.
They can be if you pay a little extra.US parachutes are unflameable.
The hole is on top of the diamond mine.
They have parachutes so they could fly
Shiver is the second track on the album Parachutes.