# How does a the vertical force of gravity end in horizontal motion?

• Boltzman Oscillation
In summary, the question is about the force that causes water to disperse horizontally when it falls in a perfectly vertical stream. The answer is radial pressure difference, which is the result of the bouncing and pushing of atoms on a macroscopic level. This concept can also be applied to droplets and is determined by boundary conditions. References can provide further information on this topic.
Boltzman Oscillation
When a stream of water falls perfectly vertical, some water hitting the surface will disperse horizontally. What is the force that causes this? References would be awesome!

Boltzman Oscillation said:
What is the force that causes this?

berkeman
Boltzman Oscillation said:
some water hitting the surface will disperse horizontally. What is the force that causes this?
To help you see why the reply by @A.T. is correct, you can picture two squishy rubber balls, dropped side-by-side touching each other. When they impact the ground at the same time, they both deform during the bounce and bulge outward on the sides. This causes the two balls to push on each other during the bounce, causing them to bounce apart instead of straight back up.

Bandersnatch
berkeman said:
To help you see why the reply by @A.T. is correct, you can picture two squishy rubber balls, dropped side-by-side touching each other. When they impact the ground at the same time, they both deform during the bounce and bulge outward on the sides. This causes the two balls to push on each other during the bounce, causing them to bounce apart instead of straight back up.

Wow that really helped me understand the concept. Now when I searched for radial pressure, I only found engineering topics. Is radial pressure not encountered in a physics curriculum? How would this apply to water? Do the individual atoms bounce apart from each other too?

Boltzman Oscillation said:
Do the individual atoms bounce apart from each other too?
On the atomic level that's what happens. On the macroscopic level we use the concept of pressure which is the average result of all this bouncing.

berkeman
A.T. said:

I would prefer to express it as Radial external pressure differences.

In other words, among others, It is the boundary conditions that determine the movement of the droplet, or of the parts of it.

miltos said:
It is the boundary conditions that determine the movement of the droplet, or of the parts of it.
The OP asks about a stream of water, not a droplet. The question is, as far I can see, about the initial horizontal acceleration of the water, not about droplet formation.

Ohhh, i didn't noticed that.
I any case, it is just a variant of the same question.

## 1. What is the relationship between the vertical force of gravity and horizontal motion?

The vertical force of gravity and horizontal motion are related through Newton's first law of motion, also known as the law of inertia. This law states that an object at rest or in motion will remain in that state unless acted upon by an external force. In this case, the vertical force of gravity acts on an object, causing it to accelerate downwards. However, if there is no other external force acting on the object, it will continue to move horizontally at a constant velocity.

## 2. How does the vertical force of gravity affect an object in horizontal motion?

The vertical force of gravity affects an object in horizontal motion by pulling it downwards, causing it to accelerate towards the ground. This acceleration is constant and is known as the acceleration due to gravity, which is approximately 9.8 meters per second squared. However, the horizontal motion of the object is not affected by this force and will continue at a constant velocity unless acted upon by another external force.

## 3. What factors influence the vertical force of gravity on an object?

The vertical force of gravity on an object is influenced by two factors - the mass of the object and the distance between the object and the center of the Earth. According to Newton's law of gravitation, the force of gravity is directly proportional to the mass of the object and inversely proportional to the square of the distance between the object and the center of the Earth. This means that the greater the mass of an object or the closer it is to the Earth's center, the greater the force of gravity acting on it.

## 4. Can an object experience both vertical and horizontal motion at the same time?

Yes, an object can experience both vertical and horizontal motion at the same time. This is known as projectile motion and is commonly seen in objects like projectiles, such as a ball being thrown or a rocket being launched. In this case, the object experiences both the vertical force of gravity and the horizontal force of the initial push or throw, resulting in a curved path.

## 5. How can we calculate the horizontal motion of an object affected by the vertical force of gravity?

The horizontal motion of an object affected by the vertical force of gravity can be calculated using the equations of motion, specifically the horizontal displacement formula: d = vt, where d is the horizontal distance traveled, v is the initial velocity, and t is the time. This formula assumes that the object has a constant velocity in the horizontal direction, which is only possible if there are no other external forces acting on it besides the initial push or throw.

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