The free fall and vertical throw they constitute the two free vertical movements, characterized in this way by having the particularity of pursuing a single trajectory from above downwards (in the case of free fall) and from below upwards (in the case of vertical throw). They are called free due to the fact that they do not have any friction force, that is, because they are considered in an abstract way that they are carried out in a vacuum.
The simplicity of these two movements, by the absence of resistance forces, makes them one of the first to join the physical science learning, common in secondary schools. In the exercises associated with these two movements, weight or mass do not intervene, and the fact that friction is not considered means that the shape of the mobile that rises or falls does not matter either.
The central thing about free fall and vertical throw is that they belong to the physical category of the rectilinear motion, uniformly varied. This means that, as stated, they pursue a single path, which do not follow it with a single speed but with a single acceleration: this acceleration is called gravity, a magnitude that on earth is approximately 9.8 meters per second, for every second.
Stated mathematically, it is about 9.8 M / S2
, and it is explained to the extent that starting from an initial position, in each second the speed will be 9.8 meters per second (a measure of speed) greater. While the physical properties of both movements they are similar, differ in some characteristics. Then themain differences between free fall and vertical throw
- :In free fall
- . The body is dropped freely from rest without being thrown in any direction, so an initial velocity equal to 0 is considered.In the vertical shot
. On the other hand, the movement is carried out from the bottom up with an initial speed, where on the way up the movement is delayed and the acceleration is downwards, and the speed upwards. The speed of the mobile stops until it reaches 0 at the highest point of the journey, from which point a free fall movement begins.
The following list will include some examples of free fall and other examples of vertical throw, exercises with their corresponding solution that facilitate their understanding.
- Resolved exercises of free fall A ball is dropped from a building, which takes 8 seconds to reach the ground. How fast does the ball hit the ground?Resolution: Advances at an acceleration of 9.81 M / S 2
- for 8 seconds, that is, it hits at a speed of 78 M / S. In the previous exercise, what is the height of the building?Resolution: The height of the building is calculated as half the acceleration, times the square of the time: in this case, it will be (½ * 9.81 M / S2) * (8S)2
- . The height of the building is 313.92 meters. An object falls in free fall and reaches a speed of 150 M / S. How long did it take to fall?Resolution
- : It takes about 15 seconds. What is the final velocity of a free-falling object that starts from rest and falls for 10 seconds?Resolution
- : 98.1 M / S. On another planet, a mobile is thrown and takes 20 seconds to reach the ground, where it arrives with a speed of 4 M / S. What is the acceleration of gravity on that planet?Resolution: The acceleration there is 0.2 M / S2
.
- Solved exercises of vertical shooting A projectile is launched vertically upwards with an initial velocity of 25 M / S. How long does it take to get to your point of maximum speed?Resolution
- : Part of the 25 M / S, and loses 9.81 every second. Therefore, it will take 2.54 seconds to reach the ground. In the previous exercise, what is the height corresponding to the maximum speed?Resolution
- : Height is calculated as half the initial speed, multiplied by time. Here 12.5 M / S * 2.54 S = 31.85 meters. A ball is thrown upward with an initial velocity of 22 M / S. What is its velocity at 2 seconds?Resolution
- : 2.38 M / S. With what initial velocity must an arrow be shot vertically upward to reach a height of 110 meters in 5.4 seconds?Resolution: As speed is lost, we start from the final and the product of time and gravity is added: 110 M / S + 5.4 S * 9.81 M / S 2
- = 162.97 M / S. How long does it take for a mobile that is thrown upwards with an initial velocity of 200 M / S to come to a complete stop?Resolution
: It takes 20.39 seconds.