Introduction to Free Fall
While studying force and motion, we have to deal with acceleration, which is a fundament of force. Again, while studying gravitational force, we talk about gravitational acceleration. This fall experienced by the falling object only due to gravity and no other entities coming into action is known as free fall. A huge object shows its gravitational effect to a tiny object near it. Thus objects accelerate towards the surface. An object having free fall experiences weightlessness.
A tiny object produces negligible effects of gravity while a very strong impact is shown by celestial objects. Everything thrown upward, after attaining a certain height, comes towards earth experiencing a free fall. All gravitational phenomena inherit free fall on a body. Outside earth, free fall becomes a more important topic to study. This article describes the concept’s origin, its impacts and applications today.
Defining Free Fall in Physics
Free fall occurs only due to one factor called and should not be disturbed by any external parameters. If so happens then the fall cannot be a free fall. When air resistance is negligible, every object falls at the same rate without regard to its mass. Free fall cannot be defined along with the action of other things (except air resistance). The motion may not always be downward. An upward motion like throwing a ball upward is also a free fall until gravity is only in action. An object keeps on floating on the moon but the same falls rapidly on earth. This is because the value of ‘g’ for earth is 6 times greater than that of the moon. As a result, the time of free fall will be longer on the moon than that on earth.
In physics, free fall is that state of fall where the body keeps on accelerating constantly without the action of other forces. Thus, every kind of fall includes free fall at some instant.
The Role of Gravity in Free Fall
Free fall is the result seen due to the consistent change in acceleration which is a cause of gravity. Gravity is incharge of this kind of weightless fall. It is a universal force attracting two bodies towards each other and this strength of pull directly depends upon the mass of the bodies and how far they are located. The falling rate is consistent and all heavier to tiny objects are laid down equally by the gravity. Thus, we can say gravity is the foundation of all free fall phenomena.
Acceleration Due to Gravity: Understanding g
Acceleration due to gravity is a constant quantity for a certain point of region but its value differs from place to place. When the mass of two objects differ in such a way that the mass of one object can be neglected as compared to the other, the force of gravity of the heavier object is determined using all constant values (g = GM/R2). Thus we can find at what rate any other tiny object comes in influence of the bigger one. For example, ‘g’ is taken as 9.8 m/s2. This means a body falls with the velocity of 9.8 m/s for every second on the earth. The value is regarded as the same for all over the earth’s surface. However, a slight difference is seen at higher altitudes and latitude. The value of ‘g’ is largest on Jupiter as it is the largest planet and hence free fall would be even of short interval.
Kinematic Equations Governing Free Fall
The free fall motion is also calculated and predicted using the equations of motion of kinematics. The air resistance is taken zero for calculation. The approximate value of ‘g’ used for calculation inside the earth is 9.8 m/s2. It may be taken positive for upward motion and negative for downward motion (direction can be chosen by oneself). Some of the equations are given below:
- v = u + at
* Here u is the initial velocity of the object, v is the final velocity after time t and a is the acceleration that would be equal to -g (a = -g) for free fall.
- s = ut + 1/2gt^2
* Here,‘s’ is the displacement produced. It is commonly used to find the height or the position of an object after a certain time.
- v^2 = u^2 + 2gs
This equation is used to determine the final velocity of an object if time is not given.
We have to note that the initial velocity is zero for dropped objects.
Factors Influencing Free Fall Motion
Free fall is solely a gravitational impact. Therefore, whatever factors affect gravity can also affect the free fall motion. Some of the factors are given below.
- Altitude: Acceleration due to gravity has an inverse relation with the distance from the center and decreases as the altitude increases. Thus, an object may have slower motion in higher altitudes than at the lower regions.
- Planetary Body: Different planets like Mercury, Jupiter have different values of gravitational acceleration. This might be due to their masses, the sun’s gravity or their rotation. Thus free fall will also be different in other planets.
- Shape and Mass: Shape and mass do not matter in vacuum so all the objects experience the same free fall. In contrast, earth has its air resistance and mass and shape cannot be neglected.
Effect of Air Resistance on Falling Objects
Air resistance acts in the opposite direction of motion and is affected by mass and size of the object. For example, a coin and a heavy stone when dropped from the same height fall at different rates. They will have the same motion only in vacuum.
Vacuum Conditions and True Free Fall
Mass makes no difference on the motion of objects in vacuum. This phenomenon can be easily demonstrated in labs with the help of vacuum chambers. We observe no effect of air resistance and all motion is uniform.
Historical Experiments and Observations
Before Galileo’s experimental findings, people believed that the acceleration was highly affected by mass. It means that a 100 kg object would accelerate ten times faster than a 10 kg object and fall faster. Aristotle first gave the concept of the motion of falling objects. It was actually true in the case of earth and was developed in school curriculum also. Later, Galileo Galilei gave his own concept on an object’s acceleration while falling which opposed Aristotle.
Galileo’s Contributions to Free Fall Understanding
Galileo’s hypothesis is not a random thought but a conclusion of strong mathematics and certain experiments and conclusions, proving his mathematics. His inclined plane experiment to demonstrate free fall developed the relationship between theories and experiments. He came to the conclusion that the falling acceleration is the same for all objects without considering their mass. This concept of free fall was a pioneer work in physics that evolved Newton’s laws of motions.
Apollo 15 Hammer-Feather Drop Experiment
The Apollo 15 Hammer-Feather Drop Experiment was a visual test conducted by astronaut David Scott on the Moon in 1971. He released a hammer and a feather at the same time to test Galileo’s theory. Both objects hit the surface together. This pictured out Galileo’s theory and confirmed it..
Real-World Examples of Free Fall
Free fall is not just a theoretical concept—it occurs in many real-world situations:
- Projectile motion: A projectile thrown horizontally or vertically experiences a free fall. When its velocity becomes zero after reaching a certain height, it comes under the action of gravity only. As a result, the object falls to the earth, showing free-fall motion.
- Falling of objects: Any objects released from a point are naturally dragged to the center of earth. For example, a coin dropped a fruit or leaf falling, rainfall etc.
- Skydiving: Skydiving is a thrilling experience that applies free-fall motion for entertainment and recreation. On jumping freely from a height, a participant experiences weightlessness and enjoys it for some moment. After the parachute is tied before landing.
- Spacecrafts in Mission: A spacecraft remains in a continuous orbit without interruption. Once the propulsion system is activated, the free-fall motion gets interrupted and the spacecraft accelerates.
- Bungee: In bungee jump also, a player falls from a certain point in a free fall motion. An elastic rope is tied to their feet for safety.
- Falling of Meteors: A meteor or a shooting star approaching toward the earth’s surface hits the surface with a free fall motion.
Common Misconceptions About Free Fall
Free fall is also misunderstood most of the time. Some common misconceptions are as follows:
- Heavier objects fall faster: In vacuum, mass doesn’t matter and is the same for all kinds of objects.
- Free fall only occurs downward: An upward motion can also be in free fall. If no other forces are acting and the object is moving under gravity, it is said to have a free fall.
- Zero gravity in space: In space objects experience weightlessness due to the negligible air resistance and not zero gravity. This makes them keep floating in space.
The Significance of Free Fall in Physics
Free fall is studied from lower classes in schools. It is used to figure out the activity of a falling body. Again, free fall motion controls every falling object with no other forces. Not only inside earth, it is equally important in outer space. To keep track of the trajectories followed by any objects, free fall must be studied. The value of acceleration due to gravity should be calculated for all regions to know the free fall motion. From space missions to the ash of an incense stick, all are covered by free fall.
Conclusions
Motion of an object is centered on gravity. In physics free fall illustrates the pure effects of gravity which are untouched by other forces of nature. Its nature has been proven long ago through various iconic experiments. Some misconceptions can be generated, looking at the nature of free fall on earth. These misconceptions must be cut out to truly define a free fall.
For the further study of the universe and to reach through other unknown surfaces, the acceleration due to gravity must be researched well. A good medical study is also required for a successful completion of any mission. To sum up, free fall is a basic concept to be thought of before thinking about any motion.
References
Drake, S. (1973). Galileo’s discovery of the law of free fall. Scientific American, 228(5), 84-93.
Naylor, R. H. (1974). Galileo and the problem of free fall. The British Journal for the History of Science, 7(2), 105-134.
Schwarz, J. P., Robertson, D. S., Niebauer, T. M., & Faller, J. E. (1998). A free-fall determination of the Newtonian constant of gravity. Science, 282(5397), 2230-2234.
SARDELIS, D. A. (1981). The Law of Free Fall: Myth and Historical Reality. Fundameta Scientiae, 2(2), 163-183.
https://www.sciencedirect.com/topics/engineering/free-fall
https://www.researchgate.net/publication/299406264_The_free_fall_experiment
