Scratch

I thought everyone learned this in science class.

velocity=speed
rate of increasing speed= acceleration

Most people just use that name because they just copy people's codes.

Last edited by archmage (2009-04-05 14:22:45)

For me it doesn't really matter unless I'm making some open-source engine.

Having studied physics for quite some time, I have a tendency to be irked when someone labels a variable "velocity" when it's supposed to be labeled "acceleration".

But, understandably, consider the age range of the community: most of them barely have been taught the technical meaning of "velocity" and "acceleration" (if at all. These terms are usually introduced and used in their technical sense in high school, which is, in most cases, the first point where physics is taught in depth) and these terms become used interchangeably.

Of course, to be more technical about it would be more clarifying when trying to understand the code.

Last edited by cheddargirl (2009-04-05 15:48:29)

Example: Person walking at 2 mph is easier to stop than baseball traveling at 90 mph.

DrMath wrote:

joeyman wrote:

Motion = A change in position over time
Speed = Rate of motion
Acceleration = Change in Speed over time
Deceleration = Decrease in Speed (Negative Acceleration)
Velocity = Speed in a given direction
Momentum = How hard a moving object is to stop

I thought that Interia was the resistance to change in velocity?

And momentum was exchanged during collisions? (Will remain in a closed-area(Can not be destroyed?) )

Inertia is sometimes described as the resistance of an object to a change in motion, the best description of it being what is put forward in the principle of Inertia (that an object stays in motion unless affected by an outside object; likewise, an object at rest will stay at rest unless affected by an outside force). Its definition can be so ambiguous at times, but for clarity, most will stick to what is put forth in the principle of inertia.

Momentum is often described as a "quantity of motion", mathematically described as the mass of an object times multiplied by its velocity. It technically is preserved "conservation of momentum", but that's only within a closed area and not affected by external force (in cases of external force, some momentum is lost by the objects involved).

If an object has no velocity, it doesn't really have momentum for itself.

Last edited by cheddargirl (2009-04-06 16:07:07)

adityasm9 wrote:

cheddargirl wrote:

DrMath wrote:

I thought that Interia was the resistance to change in velocity?

And momentum was exchanged during collisions? (Will remain in a closed-area(Can not be destroyed?) )

Momentum is often described as a "quantity of motion", mathematically described as the mass of an object times multiplied by its velocity. It technically is preserved "conservation of momentum", but that's only within a closed area and not affected by external force (in cases of external force, some momentum is lost by the objects involved).

If an object has no velocity, it doesn't really have momentum for itself.

But i thought acceleration = rate of chnge of velocity, speed=velocity only when the speed is in the same direction.
I can't understand this though:
Let two bodies have mass m1 and m2, m1>m2 if m1 is in rest, then its momentum=0, if the second body(with mass m2) hits the first body and rebounds, then its velocity is negative.Assuming that the first body does not move,
m1v1+m2v2 ( before collission) = m1v1+m2v2 (after collision) {law of conservation of momentum}
but m1v1=0 (object at rest)
so, m2v2(before collision) =m2v2(after collision), but since the object rebounds, velocity is negative which implies m2v2 = -(m2v2) how is this possible!!!!

In an isolated system of only two objects, the difference in momentum of one object in the beginning is the same as the negative momentum in the end (of that same object):

momentum(before collision) = -momentum(after collision)
(m2)(v2initial) = -[(m2)(v2final)]

Because the final velocity is negative, it cancels out the negative sign (on the right side of the equation), and both quantities are equal.

But I think this should be the end of this thread (lock it if need be), that's enough of physics already. 

Physics make the world go round?

whoa interesting

ill bear that in mind