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senox13
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Just what the title says, how do I calculate the force, in Newtons, that an electromagnet would have on an object?
senox13 said:Okay, that was helpful, but what I'm trying to figure out is more of how much magnetic force I need to accelerate a slug of a certain mass to a certain speed.
The same magnetic force as for any other force: v(t) = ∫ a(t) dt = ∫ (F(t) / m) dt.senox13 said:what I'm trying to figure out is more of how much magnetic force I need to accelerate a slug of a certain mass to a certain speed.
Hesch said:F = ( μr - 1 ) * ½ * B2 * A [ N ] , where μr is the relative permeability as for iron.
This formula is only valid when s is small compared to A.
Instantantly, the coil should only be active for a fraction of a second. As for distance, as far as it'll go after leaving the coil or coils.Drakkith said:Over what distance/time are you accelerating the slug?
The equation relating acceleration and time is: A = (V - V0)/t, where V is the final velocity, V0 is the initial velocity, A is acceleration, and t is time.senox13 said:Instantantly, the coil should only be active for a fraction of a second. As for distance, as far as it'll go after leaving the coil or coils.
Okay, allow me to rephrase myself because you seem to be assuming that my grasp of physics is nonexistent. I would have assumed that when you saw the phrase "fraction of a second," you would have understood that the word instantly was hyperbole. In doing slightly further research on electromagnets, which, admittedly, I knew very little about, I learned that although I don't need to fire the coils as precisely as I thought, though I still should try to have them active for as short a time as possible for the sake of power consumption. I suppose I should mention that this is all for a coilgun and I'm just trying to figure out how many coils and how much power I'll need to achieve the maximum possible muzzle velocity.Drakkith said:The equation relating acceleration and time is: A = (V - V0)/t, where V is the final velocity, V0 is the initial velocity, A is acceleration, and t is time.
The equation used to find the final velocity of an accelerating object is: V = V0 + At.
The equation relating force, mass, and acceleration is: F = MA
Note that in the first equation, setting t = 0 gives you a divide by zero error. In the second equation, t = 0 gives you zero change in velocity. This means that you have to have a non-zero time. Since the object only accelerates while a net force is applied (per the third equation), the force cannot be applied instantly. The time taken to accelerate the slug matters, even if it is only a fraction of a second.
There's really no easy way to figure this out if you don't know basic linear motion. There are several more equations that allow you to figure out the distance and time you need to apply the force over, but they aren't simply 'plug and play'. You have to know what each equation means and how to use and manipulate them. I highly recommend learning about basic linear motion, otherwise you'll just be floundering around in the dark. The best way would be to buy a used, college level physics textbook. I bought one for around 14 bucks from amazon, and I'm certain you can find cheaper ones. There's also plenty of websites and videos if you just search for 'basic linear motion' in google or youtube. I recommend the textbook, even if you plan to study mostly online. It will contain everything you need to know to learn about motion and will present it in an orderly fashion that makes it easier to learn. You're not bouncing around from site to site or video to video trying to figure out some concept.
Edit: Here's a physics book that's almost exactly like my own physics book and is only ten bucks used.
senox13 said:Okay, allow me to rephrase myself because you seem to be assuming that my grasp of physics is nonexistent. I would have assumed that when you saw the phrase "fraction of a second," you would have understood that the word instantly was hyperbole.
Haha, okay, fair enough. But back to the topic, how possible is it to get a muzzle velocity of 100f/s from a one to two stage coilgun? Is this an unrealistic goal?Drakkith said:Nope. Clarity is important.
senox13 said:Haha, okay, fair enough. But back to the topic, how possible is it to get a muzzle velocity of 100f/s from a one to two stage coilgun? Is this an unrealistic goal?
Eh, more or less. I know the equations and I've done my fair share of tinkering.Drakkith said:Before we get to that, do you know anything about basic electronics and electrical circuits?
The force from an electromagnet can be calculated using the formula F = BIL, where F is the force in Newtons, B is the magnetic field strength in Tesla, I is the current in Amperes, and L is the length of the wire in meters.
The force produced by an electromagnet is directly proportional to the current passing through the wire. This means that increasing the current will result in a stronger magnetic field and therefore a greater force.
The length of the wire also plays a role in determining the force of an electromagnet. The longer the wire, the larger the surface area and the stronger the magnetic field, resulting in a greater force. This is reflected in the formula F = BIL, where L represents the length of the wire.
The magnetic field strength, represented by the variable B, indicates the intensity of the magnetic field produced by the electromagnet. The stronger the magnetic field, the greater the force that will be exerted on any nearby objects or materials.
In addition to current, length, and magnetic field strength, the number of turns in the wire, the type of core material, and the size and shape of the electromagnet can also impact the force produced. These factors should be taken into consideration when designing and calculating the force of an electromagnet.