Noob Physics questions.

[Apple-Juice]

As always, my I NEED AS PLOX help thread will begin with stating that i'm a beginner with AS2, please be fully aware of this.

Now, what i'm trying to make is a game in which an object is launched straight up into the air by a device, what i want to know is what would be the physics formula for this?
i can convert it to AS myself, i just need to know how one determines how high an object goes, what it's velocity/acceleration will be after it's launched by a machine with a set amount of power, and how the objects weight affects this.

again, just some formula's or even pieces of formula's would be splendid! thanks :).

[Toast]

At 6/3/09 02:35 PM, Apple-Juice wrote: Now, what i'm trying to make is a game in which an object is launched straight up into the air by a device, what i want to know is what would be the physics formula for this?

a = g

[Apple-Juice]

At 6/3/09 02:37 PM, Toast wrote:

At 6/3/09 02:35 PM, Apple-Juice wrote: Now, what i'm trying to make is a game in which an object is launched straight up into the air by a device, what i want to know is what would be the physics formula for this?

a = g

a=vg

[Toast]

On any non-eletrically charged body on earth, the gravitational acceleration, denoted g, is approximately 9.81m/s^2.

a = g = 9.81m/s^2

Weight doesn't affect gravitational acceleration.

F = mMG/d^2
F = ma
therefore a = F/m
and thus F = mMG/d^2/m = MG/d^2
(product of mass of earth and distance from earth's gravitational center, divided by distance squared)

Mass of the object makes no difference.

All you need is a = g

[Toast]

At 6/3/09 02:46 PM, Toast wrote: On any non-eletrically charged body on earth, the gravitational acceleration, denoted g, is approximately 9.81m/s^2.

My bad, the standard gravity is the same for electrically charged bodies too. What I meant to say is that the total acceleration of your ball is g assuming it is not eletrically charged.

[Apple-Juice]

Thanks toast, that was helpful. I have another question though.

http://spamtheweb.com/ul/upload/030609/5 1918_take_a_big_jump.php

here i calculate my initial velocity, how would i determine the distance it travels and how much air time it gets?
V-=g/myframe rate?

[Cryoma]

D=(1/2)*CD*A*r*V^2
Where CD is called the drag coefficient, which is a number that depends on the shape of the object [for a smooth sphere, CD~0.5],
A is the cross sectional area of the object,
r is the mass density of the fluid (about 1.2 kg/m3 for air, 1000 kg/m3 for water),
V is the speed of the object with respect to the fluid.
The acceleration produced by this force would be:
ax = -D/m

[Apple-Juice]

At 6/3/09 05:47 PM, Cryoma wrote: D=(1/2)*CD*A*r*V^2

Thanks but i'm actually looking for a slightly dumber solution :P

[Toast]

At 6/3/09 05:47 PM, Cryoma wrote: D=(1/2)*CD*A*r*V^2
Where CD is called the drag coefficient, which is a number that depends on the shape of the object [for a smooth sphere, CD~0.5],

What are you talking about? This doesn't make any sense. We're not in fluid dynamics here, OP is simply looking for simple classical mechanics formulae to determine speed and acceleration of his ball.

Besides, the drag coefficient is defined by the drag force divided by half of the product of the density of the fluid and the speed of the object of the reference area.

OP: I gave you the relation for acceleration. Velocity is simply your initial velocity + acceleration.

What more do you need?

[UnknownFury]

At 6/3/09 05:31 PM, Apple-Juice wrote: here i calculate my initial velocity, how would i determine the distance it travels and how much air time it gets?

You can use the equations of motion (Wikipedia)

For example, to get air time, you would know u, v and a so you can use the formula:
v = u + at
t = (v - u)/a

That would give you the time taken to reach the peak of the projectiles flight and it will take the same time to fall again so multiply it by 2.

Make sure you separate your x and y components when using these equations. In this example we would only work with y components

[Toast]

At 6/3/09 05:31 PM, Apple-Juice wrote: here i calculate my initial velocity

We can't decide the initial velocity for you. You told us the object is launched in the air by a device, without telling us with how much energy this object is launched. If you tell us the energy in joules, we can work out the velocity provided you give us the weight of the object.

[Apple-Juice]

At 6/3/09 06:29 PM, UnknownFury wrote: v = u + at
t = (v - u)/a

hmm, this is similar to something i tried, (since my final velocity on the way up is 0 i just used t=v/g)
but it gave me unrealistic figures.

At 6/3/09 06:34 PM, Toast wrote:

At 6/3/09 05:31 PM, Apple-Juice wrote: here i calculate my initial velocity

We can't decide the initial velocity for you. You told us the object is launched in the air by a device, without telling us with how much energy this object is launched. If you tell us the energy in joules, we can work out the velocity provided you give us the weight of the object.

you didn't click the button toast :P. i already calculate it. click the start button twice and you'll see.

[Toast]

Misread it as "How do I calculate my initial velocity" :P

[Cryoma]

Oh, determine, I thought he wanted something to modify the acceleration.

Mah bad.

[Toast]

Air resistance can be considered as a constant, you don't need to use fluid dynamics to calculate it in flash. It's not something that changes in function of time, since th acceleration is constant.

[Cryoma]

I use fluid dynamics for everything.
It's just my style.

So I'll stop trying to help.

[Apple-Juice]

http://spamtheweb.com/ul/upload/030609/5 9553_take_a_big_jump.php
updated. thanks for the help so far :).

At 6/3/09 07:01 PM, Toast wrote: Air resistance can be considered as a constant, you don't need to use fluid dynamics to calculate it in flash. It's not something that changes in function of time, since th acceleration is constant.

alright, that's understandable, how would i add air resistance into the equation?

[Toast]

At 6/3/09 07:34 PM, Apple-Juice wrote: alright, that's understandable, how would i add air resistance into the equation?

If your project nweeds near 100% physical accuracy, then you can use fluid dynamics to determine the resistance force by the air using the formulae that were posted in this thread. However, since I doubt you're gonna be needing this much precision, air resistance is negligible. You're probably not recreating real-life scale in your flash, which will cause inaccuracies more important than air resistance, and thus air resistance is not noticeable.

[Apple-Juice]

At 6/3/09 07:57 PM, Toast wrote: and thus air resistance is not noticeable.

ok, on another note, one feature of the game is that you can make upgrades to increase aerodynamics to move quicker and go father. would a faux-equivalent of this be a velocity boost?

[Toast]

At 6/3/09 08:04 PM, Apple-Juice wrote:

At 6/3/09 07:57 PM, Toast wrote: and thus air resistance is not noticeable.

ok, on another note, one feature of the game is that you can make upgrades to increase aerodynamics to move quicker and go father. would a faux-equivalent of this be a velocity boost?

Features similar to rocket boots would be the equivalent of initial velocity boost and increased momentum on the way up. Features like a special suit to move faster in air would simply remove air resistance and make the velocity higher (gravitational acceleration remains the same, but the character moves faster)