# Why do objects fall to the ground

## Do things fall at different speeds when falling?

You drive your rowing boat towards the waterfall up on the river. Unfortunately, you failed to turn back in time and now watch the boat, your hat, the fishing rod, and yourself fall down. The water falls too. Of all of these things, which comes down to the bottom first? In other words: will you be able to overtake the waterfall falling? No. "All bodies fall at the same speed." That is the law of fall, scientifically formulated by Galileo Galilei. However, this law of fall is hardly seen in everyday life, since air resistance falsifies the fall of things. In practice, therefore, different bodies fall at different speeds. They only fall observably at the same speed when they have the same shape and thus their air resistance is the same. You will not be able to overtake the waterfall falling. We also have to look closely at what “same fast” means. What has been falling for a long time is of course faster. So hardly any things fall at the same speed. The sentence is meant like this: Are falling things accelerated differently? The answer: no.

You can see the law of fall mathematically and completely without air in the formula with which you can calculate the speed of the accelerated movement. Here the mass of the object does not appear at all, only the magnitude of the acceleration and the time of the fall: v = at (speed = accelerationTime)

Under "ideal conditions" - which are probably not your ideal conditions, but this is what physics calls the absence of interference, so: under ideal conditions, the boat, fishing rod, your hat and you and the surrounding water come at the same time at the bottom of the Waterfalls. You fail to overtake the waterfall falling. [/tab]

A half-full water bottle hits the ground at the same time as a full water bottle. The law of fall is visible here because both bottles have the same shape and thus the same air resistance. Try it! If you hear a bang on impact, they arrived at the same time. The ear is a very good and much more precise measuring tool than the eye.
A feather falls on the moon as fast as a hammer. The law of fall is really and amazingly visible here, because the air resistance on the moon is completely absent. However, only the astronaut who did the experiment saw it.

What is speed

The speed is a measure of how quickly an object changes its current location. What distance does the object cover in a certain time? When the object is at rest, the speed is zero.

Calculating the speed

v = s / t

v ... speed
s ... change of route
t ... time

Uniform movement. This formula always applies if the speed does not change (overland travel on the motorway) or if an average speed is to be calculated (travel from Vienna to Salzburg). There is also the concept of instantaneous speed, the speed indicated by the speedometer.

Note: All calculations are to be carried out in the basic units of meters, kilograms and seconds so that the correct and comparable sizes / units / numbers come out.

What is acceleration?

The acceleration is a measure of how quickly an object changes its current speed. Which speed change takes place in a certain time? If the speed does not change, then the acceleration is zero.

Calculation of the acceleration

a = v / t

a ... acceleration
v ... change in speed
t ... time

Uniformly accelerated movement. This formula always applies if the acceleration does not change or if you want to calculate an average acceleration.

Note: All calculations are to be carried out in the basic units of meters, kilograms and seconds so that the correct and comparable sizes / units / numbers come out.

Which types of movement do you differentiate?

The simplest form of movement is that in which the speed does not change. It is called uniform rectilinear motion. It gets a little more complicated when there is acceleration and the speed changes. In the case of constant acceleration, we speak of uniformly accelerated motion in this case. In free fall, for example, the acceleration does not change over time.

Where does acceleration come from?

An acceleration is always caused by a force. This is also the physical definition of force: a "something" that causes acceleration when it acts on a mass. The larger the mass, the smaller the acceleration achieved when the force occurs.

Force: Newton's second axiom

F = m * a

F ... force
m ... mass
a ... acceleration

This formula shows the relationship between force, mass and acceleration. It always applies when a body changes its speed and the cause of the acceleration was a force.

Note: All calculations are to be carried out in the basic units of meters, kilograms and seconds so that the correct and comparable sizes / units / numbers come out.

Are there any special accelerations?

Most accelerations will change over time. In the car, for example, it changes depending on the engine speed. An incredibly uniform acceleration, on the other hand, is the acceleration of gravity. It attracts all objects with an acceleration of a = 9.81 m / s² and increases their speed by 9.81 m / s per second.

Where and how does gravitational force work?

The gravitational force acts between two or more masses and has an infinite range. It decreases the further apart the masses are. By the way, weightlessness only prevails where the gravitational pull of the moon and earth cancel each other out.

Path calculation during free fall: Uniformly accelerated movement

s = a / 2 * t ^ 2

s… way
a ... acceleration = 9.81 m / s ^ 2
v ... speed
t ... time

Since the speed increases with the accelerated movement, an increasing distance is covered per second. This could make it difficult to figure out the total route, but this formula does it nicely for you. It is a result of the integral calculus.

Note: All calculations are to be carried out in the basic units of meters, kilograms and seconds so that the correct and comparable sizes / units / numbers come out.