This Mythbusters episode is focusing on two myths today. Each has one experiment, one regular video with an explanation and a cooler video that doesn't explain everything but is fun to watch anyway.
Also; the small, unnamed arrow means the direction in which the ball is traveling.
An object always moves in the direction of the net force exerted on it.
If the object always moves in the direction of the net force and a basketball is thrown in one direction, then it will keep going in that direction.
This FBD shows projectile motion, the ball is simply thrown forward.
The ball now moves back toward the person that threw it but the net force shows that it should still be going down.
As seen in the FBDs the ball continued forward like normal projectile motion but when it hit the ground, according to the 'myth' it should have stopped. But it moved back up forward with the net force in a downward direction. This theory is not always true and therefore disproved. BUSTED!
Most people believe this myth because it is usually true. Most of the times it is not then most people regard it as another force acting on it that they don't understand. It also gives a rational reason for why things are the way they are and people will put their trust in something that is mostly true if there isn't anything that can be all true.
An object always changes its motion if there is a force exerted on it by other objects.
If an object always changes in motion if there is a force exerted on it by other objects then a ball rolling toward a container should change direction when it hits it.
This is the FBD of the ball after it has left the foot so no other applied force is acting upon the ball.
As can be seen, the direction of the ball didn't change even though another force is acting upon it.
The ball didn't change direction even though it hit the container. The second FBD disproves the myth by showing that even though other forces were exerted on it it did not change direction to conform to those that force.
The ball did not change its motion even when another force acted upon it. Even though it was a small force, it still did not change therefore disproving the theory. The before equation is BUSTED!
This myth is believed anyway, even though it can be disproved, because, usually it is true and it also deepens, if a person gets really specific on angle, a very small force can change the direction of the object. This myth explains many things in our world and it is much simpler to believe in what is mostly true and try to apply it to all.(at least all relating to the subject)
Awesome video to myth #1;
Awesome video to myth #2;