On Earth, why don t a piece of paper fall at the same time as an iron ball

It was in a vacuum, and a piece of paper and an iron ball fell to the ground at the same time!

In a normal environment, the air resistance of the paper is much greater than that of the iron ball, so they will not fall at the same time!

There is no air in a vacuum, so there is no air resistance! So the acceleration is the same, so land at the same time!

To be precise, a large iron ball and a small iron ball cannot land at the same time, because the air resistance is proportional to the quadratic of their linearity, and the mass is proportional to the cubic of the mass, so it should be the big iron ball that lands first. However, for iron balls, the influence of air resistance on motion is actually very small, but for paper pieces, air resistance cannot be ignored.

The answer upstairs is questionable. The air resistance of a piece of paper is not necessarily greater than that of an iron ball, but because the mass of the paper is small, the gravity is small, so the air resistance is relatively large. The mass of the iron ball is very large, and although the air resistance is about the same as that of paper, the gravity is much smaller than that of the iron ball, which can be ignored.

Neither is right, to be precise, it falls to the ground at the same time in a vacuum, but when the paper and the ball fall at the same time in the vacuum, it is found that the paper hits the ground first, and the force in the vacuum conflicts with classical mechanics. Just like in classical mechanics, a circular motion requires a centripetal force, but in the nucleus it is not needed... You can look it up on the Internet.

Regardless of the air resistance, it can be seen that both balls are in free fall, and there is a kinematic formula h=1 2gt 2, and it can be seen that time t is only related to height h, and the height is the same, so the time is the same.

If the air resistance is considered, because the mass is the same, and the density of the paper is small, the volume is large, and the air resistance is large, there is Newton's second law mg-f=ma, the gravitational force mg is the same, a, f is the paper ball resistance and acceleration a; f'The drag and acceleration of the iron ball, f is greater than f', a is less than a', by kinematics company, h=1 2at 2, available, the iron ball takes a short time, first landing

Regardless of air resistance, the acceleration of a free-fall motion of an object of any mass at the same place is g=mg m

The acceleration due to gravity experienced by the object is the same.

The reason why you can't land at the same time is because of the presence of air, and different objects are subjected to different resistance by air.

This drag affects the speed of the fall.

Relative to its own mass, the air resistance of the paper is greater than that of the iron ball (the mass of the iron ball itself is large, and the air resistance is negligible).

So the acceleration is different.

You can crumple the pieces of paper into a ball (reduce the contact area with the air and reduce air resistance) or replace them with stones and other heavier objects.

The so-called two iron balls landing at the same time only occurs when the air resistance is not counted or the same, and this experiment is generally done with objects with the same shape and different masses.

The contact surface between the paper and the air is large, and it is subjected to relatively large air resistance, which is negligible. If you put a piece of paper, a small ball, etc. into the vacuum test equipment and fall at the same height, the time taken is the same.

The premise that two iron balls land at the same time is that the resistance is the same when falling. (It is also an iron ball, so the resistance is probably the same during the experiment, and the result of landing on the ground at the same time is the end).

It is impossible for a piece of paper and a ball of iron to hit the ground at the same time under normal circumstances. In the laboratory, in a vacuum container, the paper and the iron ball can be hit the ground at the same time, didn't your physics teacher do this experiment for you before? I remember our teacher doing this experiment before:

Cotton and balls.

There is air resistance. If it is in a vacuum, it will fall to the ground at the same time.

The resistance to air is different from the gravitational force of an object.

Landing at the same time. Remember the scientist Galileo experiments.

The name of that story is "Two Iron Balls Landing at the Same Time". Before Galileo, Aristotle in ancient Greece.

It is believed that the speed at which an object falls is not the same. The speed at which it falls is directly proportional to its weight, and the heavier the object, the faster it falls. For example, an object weighing 10 kg will fall 10 times faster than an object weighing 1 kg.

For more than 1,700 years, people have treated this as contrary to the laws of nature.

The doctrine of the doctrine is an unquestionable truth. The young Galileo, reasoning from his own experience, boldly questioned the doctrine of Archelia Estotle. After much deliberation, he decided to do a hands-on experiment. He chose the Leaning Tower of Pisa.

as a testing ground. On this day, he brought two iron balls of the same size but different weights, one weighing 100 pounds and being solid; The other weighs 1 pound and is hollow. Galileo stands on top of the Leaning Tower of Pisa and looks down.

Aristotle's dusty theory cannot be wrong! The experiment began, and Galileo took an iron ball in each hand and shouted: "People below, you see clearly, the iron ball is about to fall."

With that, he opened both hands at the same time. It was seen that two iron balls fell parallel to each other, almost simultaneously on the ground. Everyone was dumbfounded.

Galangelo's experiments revealed the secret of the falling body movement and overthrew the Arisian doctrine of Madotus. This experiment is of epoch-making significance in the history of physics.

The paper is approximately flat and falls downward, with a large area of the lower bottom surface and is subject to greater air resistance, and its mass is small, so the acceleration becomes significantly smaller; The resistance of the iron ball when it falls is negligible compared to its mass.

The force analysis is as follows:

The magnitude of the air resistance is related to the size of the projection of the contact area on the perpendicular plane in the direction of motion, and also to the speed of motion.

The projection of this area of the iron ball is always the same size, but the piece of paper can easily begin to move in the direction of its own plane similar to a pendulum, until the vertical resistance is less than the gravity, and then continue downward, and the trajectory is zigzag.

In addition, the paper is relatively small in mass and the speed is easy to change.