God-fucking-damn it, Sanure. Physics does not work that way.
PHYSIC DOES NOT WORK THAT WAY.If you threw the rock, then the force acting upon it was you and only you. In this case, the forces acting upon it are momentum and gravity and weight.
False. First off, momentum is velocity times mass. It's not a force that affects an object's trajectory. Secondly, weight is not a force acting on the object either. Well, it's the force of gravity on the object, but you also included the force of gravity. So I have no idea what you were trying to say with it. Thirdly, that's not how forces work. The force of gravity is constant. Throwing a rock doesn't remove the force of gravity. Juts cancels it out so that the rock sails upwards.
If I threw a rock using magic, it was still me that threw it using magic. in this case the forces acting upon it are Momentum, gravity, and magic.
Nope. The forces are gravity and magic. And the force of magic disappears when the spell ends.
For movement to occur the forces acting upon an object must remain constant or, if a change in direct is caused, stronger than the origin of movement.
If Newton is not spinning in his grave, then I shall construct a coffin-spinning device so that he will be. Newton's First Law of Motion: Objects in motion continue to stay in motion. Objects at rest continue to be at rest.
Unless acted on with an outside force. That's the key part here. Adding a force makes a object accelerate. Removing a force does not make it deaccelerate. You have to add a force in the opposite direction instead.
Thus, if the force acting upon an object was caused by magic and you apply a force greater than the magic, in this case Magic cancelation, the object would either change direction, or stop moving. Since the movement of the boulder thrown by magic was magic, removing the magic completely would cause a downward change in direction. It isn't canceling out the force altogether (since that would make the boulder float) but is instead changing it due to a stronger force acting upon it. it would still enter the anti-magic field, it would still be moving, but it's intended direction would change toward the ground and would no longer be directed towards the target.
This is the part where you are almost right for the wrong reasons. Magic cancellation doesn't exert a force on the object. It just removes the force cause by magic. So the object wouldn't stop moving, it'd be continuing to move in the direction in it was moving due to Newton's First Law. So the only remaining force acting upon it is gravity, which exerts a force downward on the boulder. But that wouldn't cause the rock to immediately move down towards the ground. The velocity perpendicular to the force of gravity is going to remain unchanged, so the rock will keep flying forwards as it accelerates downwards, making its path through the air a parabola.
@USEC, I do understand that Force makes Acceleration which makes velocity. However, Physics isn't just one sided like that. It has multiple factors which determines path, speed, weight, etc. All of these factors determine where it will go or impact. changing one changes the end result.
NO IT FUCKING ISN'T.
PHYSICS KINEMATICS IS FUCKING ONE-SIDED LIKE THAT. Velocity, acceleration, force, time, mass and friction are the only factors that matter for a single-body problem like this fucking shit. And yes, changing one changes the end result, but we're not talking about a specific case. We're talking about a general case here, where we can abstract everything down to those few factors.
It does have momentum applied to it and gravity which gives it an arc path instead of the magic used to propel it forward. It wouldn't hit the target since no advanced planning was used to make sure the boulder hit. It would land inside the Anti-magic field, but the location of it impacting would not be the intended due to the forces acting upon it being different than when it started.
Again, momentum isn't something that makes an object go. Momentum is something that a moving object innately has.
3. Knowing whether they planned or not is an unknown. I assume that they didn't since the conversation was not going into hypothetical situations. The only known was guy throws a boulder at a person in a anti-magic field using magic. Rolling would work. Gravity is your friend in that case.
It's not an unknown. We were specifically talking about getting around a magic field by magically flingly rocks at it. So the person doing this is definitely planning to hit something and would compensate accordingly.