Why do raindrops move at a uniform speed instead of freefall?

Raindrops are indeed in free fall when they first form their fall.

But there is a very important condition for free fall.

That is, in the absence of air resistance.

As the raindrops fall, the air resistance increases.

In the end, it is equal to the gravitational force of the raindrops.

At that point, the raindrops can't accelerate, they become constant.

The relation of the air resistance of a moving object is f=kv is a constant.

The raindrop is subjected to air, wind, and other resistance equal to its gravity.

The raindrop is in free fall, but it is affected by the updraft and the flow of air, so its movement is irregular.

Free fall is only the force of gravity

In addition to gravity, the raindrop is also resisted by the air, and it should be in a uniform acceleration motion f ma

f f gravity f resistance.

The resistance of the wind is proportional to the speed of descent in square terms, and the greater the speed, the greater the resistance. When the raindrops fall, they start at an accelerated motion, and when the drag reaches the same level as gravity, they move at a uniform speed. If the freefall falls to the ground, the speed is very high, and it must crush people to death.

There are several reasons for this:

1. The raindrops are liquid, and the density is not large.

2. The speed at which the rain falls is still not enough.

3. The existence of air resistance and wind, the raindrops are not pure free-fall motion, so the absolute speed is not necessarily very large when they reach the ground, and the action of the wind divides the raindrops into smaller or thinner, and at the same time, the falling direction of the raindrops is offset to further reduce the speed.

The free fall motion is only affected by gravity, and the raindrops will be affected by air resistance and will slowly change to a uniform motion. Imagine if it is a free fall, so high a distance, how much impact will it have when it falls?

It is a free fall, but the raindrops gradually condense and become larger, and they are also affected by air resistance, so it is not painful to hit someone.

In addition to gravity, there is also air resistance and wind power.

Suppose it is a free fall, from vt squared - v0 square = 2gh, vt = 141m s, so it is not free fall.

Assuming that it is moving in a straight line at a uniform velocity, then there must be at least one force (or the resultant force of multiple forces) that is equal to gravity, and during the movement of raindrops, there is no force other than gravity and air resistance, and if the air resistance is always in the opposite direction of gravity, then the raindrop will not be able to fall, because the raindrop has no initial velocity.

Therefore, the fall of the raindrop is first accelerated and then moved in a straight line at a uniform speed. The reason is that air resistance is related to speed, and the higher the speed, the greater the air resistance. When the velocity reaches a certain value, the air resistance and gravity are reversed, the velocity no longer increases, and the force is balanced, so it moves in a uniform linear motion.

1. Start to approach the free fall motion (close to uniform acceleration motion).

2. As the velocity increases, the drag becomes larger until it is equal to gravity, that is, the acceleration gradually decreases.

3. When landing, it should be close to a uniform motion.

At the beginning, it was a free fall movement, and then it was a 4m s constant motion.

This is because the air resistance experienced by the raindrops in the air is related to the velocity. The phenomenon is explained as follows:

The raindrops are subjected to two forces during their fall in the air, one is the vertical downward gravity, and the other is the air resistance that is opposite to the direction of falling, and the air resistance hinders the falling motion of the raindrops. At the beginning, the gravitational force of the raindrop is greater than the air resistance, the direction of the resultant force is downward, the raindrop accelerates downward, the falling speed continues to increase, and the air resistance also increases sharply (the air resistance is related to its velocity, and the magnitude of the resistance is proportional to the square of the velocity), the downward resultant force is getting smaller and smaller, and the acceleration is getting smaller and smaller, when the velocity increases to a certain value, the air resistance is balanced with gravity, and the acceleration is 0, at this time, the velocity reaches the maximum and no longer increases. After that, under the action of inertia, the raindrops begin to move in a straight line at a uniform speed (falling at a uniform speed).

In disregard of air resistance.

In the case of force, the fall of the raindrop is a uniform acceleration motion, and its acceleration is the acceleration due to gravity, i.e., g=980 cm sec2.

When considering the deceleration effect of air resistance on the raindrop, the raindrop starts with g as an acceleration motion, and with the acceleration of the speed, the air resistance increases, and gradually becomes an acceleration motion less than g, then becomes a deceleration motion, and finally becomes a constant velocity motion when the resistance increases to equilibrium with gravity.

The specific process is shown in the figure below (note: the ordinate is [height], the abscissa is [speed], not time).

The air resistance experienced by the raindrops when they fall is proportional to the falling speed, so the raindrops falling is a kind of variable acceleration linear motion Not the free fall motion that is said downstairs, the free fall motion is a uniform acceleration linear motion.

As the raindrop velocity increases, the air resistance of the raindrop increases, so the combined acceleration of the raindrop decreases. When the falling height is large enough, the raindrop will fall at a certain maximum, and the air resistance will be equal to the gravitational force of the raindrop, and then the raindrop will move in a straight line at a uniform speed. Considering the whole process, the raindrops should be in a linear motion with variable acceleration.

If gravity is not taken into account, it is a free-fall movement.

First it was a free-fall motion, and then it became a rapid linear motion.

In summer, it generally falls around 5000 meters.

In the south, it generally falls around 2000 meters in winter.

Although rainwater is not pure water, it approximates pure water. 20 drops of pure water is one milliliter, that is, liters, and the mass of one liter of water is 1kg, then the mass of one drop of water is kilograms = grams. In summer, it is relatively larger, about the grams.

There is only one drop of rain in the summer, and if you count the whole process of rain, there is so much to know.

e=mgh=

What is the concept of 5J? It's about ten meters above your head, an egg falls and hits the kinetic energy you give you.

Imagine that if there is no resistance from the air, the next rainstorm in the summer will be countless eggs thrown on your head.

Why do raindrops fall from high in the sky at a constant speed before they hit the ground?

Objects are subject to air resistance during their actual fall. In the case of a very short falling distance, the velocity of the object is not large, and the air resistance can be ignored, and the free fall of the object can be regarded as a uniform acceleration motion --- free fall motion.

But when the falling distance is larger, the speed of the object will be very large, at this time the resistance of the air can not be ignored, the greater the speed, the greater the resistance, the resultant force of the object is mg-f resistance = ma, when the speed increases to a certain extent, the size of the resistance is equal to gravity, the resultant force is zero, the acceleration is zero, and then the object will do uniform linear motion. This is the reason why raindrops move at a uniform speed for a period of time before they reach the ground.

The greater the speed of the raindrops, the greater the air resistance, and Spider-Man said that "with great power comes great responsibility".

Because when the raindrops start in the air, the speed is not fast, and the air has little resistance to it, so the raindrops are almost in free fall.

As the velocity increases, the resistance is proportional to the square of the falling velocity, that is, the drag is getting bigger and bigger, and the acceleration is getting smaller and smaller.

When the resistance is equal to the weight of the raindrop, the raindrop is balanced by the force, and the raindrop will move at a uniform speed.

Raindrops fall from hundreds or even thousands of meters in the air, and the effect of air resistance on them is very obvious. Whether it is a heavy or light raindrop, no matter how high the dark clouds fall, it has been accelerating, and before it descends to the ground, it has already reached its ultimate speed. The ultimate speed is only related to the weight, and the heavier the raindrop, the greater its ultimate speed.

In the end, the conclusions were: first, when the raindrops landed, they all moved at a uniform speed; Second, the speed of heavy raindrops is faster than the speed of small raindrops!

The underside of the water droplet is affected by the air resistance (airflow) and changes its shape, and finally the air resistance is equal to the gravitational force.

Yes, water molecules become water droplets because there is an internal tension between multiple water molecules, just like a bunch of children holding hands, when the water droplets fall, the internal tension of the water molecules will not change, but with the increase of the speed of the water droplets, the resistance of the air to the bottom of the water droplets will gradually increase, which will make the uneven force at the bottom of the water droplets changeIn fact, if the space is long enough, the droplets aren't getting thinner, they're closer to the streamline, and if you're going to be aerodynamics, you're going to understand very well.

There are two explanations:

1。Explained by the relationship between air pressure and flow velocity.

When the water flows, the gravitational potential energy is converted into kinetic energy, the speed increases, and the surrounding air is also driven, flowing faster and faster, the flow velocity is large, the pressure is small, and the outer layer of air is pressed inward, making the diameter of the water flow smaller.

2。Explained in terms of traffic.

When the water flows, the gravitational potential energy is converted into kinetic energy, the velocity is accelerated, and the flow rate is always constant, according to Q (flow rate) = SV (Q = V t = SV), the cross-sectional area becomes smaller, and the diameter becomes smaller.