Mythbusters

In this episode of Mythbusters, we (Abigail, Tori, Sabeeh, and Will) fearlessly set out to disprove wrongly believed physics myths. We gallantly disproved these myths in order to  preserve physics' integrity and save lives. After all, misunderstanding science can be dangerous.


Myth 1:
The first wrongly accepted myth is stated thus: An object always moves in the direction of the net force exerted on it.
This is false. An object usually moves in the direction of this force exerted on it , but not always. If an object always moves in the direction of the net force exerted on it, and we throw a basketball on the ground, then it won't bounce back into the air, because gravity would be the only force acting on the basketball. To disprove this myth, the bold mythbusting team threw a basketball at the ground, from whence it proceeded to bounce back into the air. This is a classic example of projectile motion.

The forces acting on the basketball after it bounces look like this:

As you can see in this sum of the forces, the only force acting on the basketball while it's in the air is gravity. (The unattached arrow represents direction.)

 According to the false myth, the basketball should be falling faster than the wreckage of a sky pirate ship. In fact, if the myth was true, the ball wouldn't have gotten off the ground at all. Because the basketball is moving up, the myth is busted.


Myth 2:
The second myth is theorized so: An object always changes its motion if there is a force exerted on it by other objects.
This myth is also false. Most objects change their direction when there is an outside force exerted on it, but some objects just ignore outside forces and keep going. If an object always changes its motion if there is a force exerted on it by other objects, and a ball has normal force exerted on it by a tube then it will change directions. Once again, the intrepid group of mythbuster set out to disprove a myth. This time, we rolled a basketball at an empty, defenseless tennis ball tube.

Proof!:

When the basketball hits the empty tennis ball tube, it ignores it like a steamroller ignores a squirrel. The FBD of ignorance that strong looks like this:

(The unattached arrow represents direction.)
The empty tennis ball tube exerts a normal force on the basketball when the basketball hits it, as shown in this sum of the forces acting on the basketball:

Even though there is a force acting on the basketball, its motion isn't affected in any way whatsoever, rendering the myth busted.


Termination (it's a legitimate synonym for conclusion):

In the end, my troops and I did what we set out to do. We disproved myths. In fact, we did so well, that we disproved all of the myths!

Now, you may be asking yourself, 'If these myths were so quickly disproved by a motley crew of high school freshman, why would the human population in general believe them?' My answer to you is this: they don't. The human population in general doesn't think about physics, probably because it's the most mindblowingly awesome subject ever. But if the world did hypothetically think about physics all the time, they might still believe these myths.
But why? Is it because human ignorance is as flagrantly obvious as a volcano full of molten lava in your face? (I really hope that never happens to anyone. It would be really painful.) I don't think ignorance is the problem. The birth of these myths is rooted in misguided logic. I mean, they sound pretty reasonable.
The first myth's origins are obvious. The hypothetical, misguided physics geniuses (genii only applies to spirits, demons and qualities) construct FBDs of their daily movements, and they notice that whenever they exert a force, they move in that direction (walking, running, swimming, skating, snowboarding). However, these physics geniuses didn't continue to construct FBDs for all of the other aspects of their lives, or they quickly would have realized that their theory was wrong.
The second myth also seems like common sense. When you run into something, like a sumo wrestler or a giant cube of jello, you tend to bounce off. The prodigies of the hypothetical physics world were quick to figure out that your motion changed because the sumo wrestler and the jello exerted a force on you. Or maybe they just played pool frequently. In any case, the fault in this theory was that they weren't empathetic enough. If they had put themselves in the sumo wrestler's shoes, or the jello's shoes, they would have known that they didn't move at all.
The laughable physics geniuses' foibles live on in the mind of real people, ones who don't really construct FBDs for every situation. This is why the masked crusaders, known only as the 'Mythbusters', continue to redistribute the wealth of knowledge.