In our daily life we can say that free fall movement is impossible, since we cannot avoid the influence of air resistance. The only way to get a free fall movement is in a laboratory through a device called a Newton tube. In this device, a vacuum is achieved by removing the air through a suction pump. With this device we can consider, with good approximation, a free fall movement.
When a body is in free fall motion, it is subject to only one force, the weight force. The weight force acting on a free falling body acts in the same direction as the movement, so this movement is of the MRUV type (uniformly varied rectilinear movement). Thus, we have the possibility to use the mathematical functions that describe MRUV.
In order to facilitate our study of free fall movement, we can substitute some variables.
- we saw that the trajectory that the body describes in the free fall movement is always straight and vertical, we can substitute the variable S (position) for the variable H that is associated with the vertical axis.
- the modulus of the acceleration of the body in free fall is equal to the modulus of the acceleration due to gravity (g).
- the reference axis is a vertical axis, oriented downwards, with the origin fixed at the point where the body will be dropped.
- under the conditions above: the initial position of the body and its initial velocity are null (H = 0 and v = 0).
- as the acceleration due to gravity is (g) and is oriented downwards, its value will always be a positive value.
Below we have a table with the main functions of the MRUV and the respective functions of the free fall movement.
By Domitiano Marques
Graduated in Physics
Source: Brazil School - https://brasilescola.uol.com.br/fisica/funcoes-horarias-que-descrevem-movimento-queda-livre.htm
