Rail Guns and acceleration

by lylos
Tags: acceleration, guns, rail
lylos is offline
Mar29-07, 09:40 PM
P: 79
1. The problem statement, all variables and given/known data

A conducting bar with mass=25.0 kg and length L=51.0 cm slides over horizontal rails that are connected to a voltage source. The voltage source maintains a constant current I= 2400A in the rails and bar, and a constant, uniform, vertical magnetic field B = 0.480 T fills the region between the rails.
See figure:

It has been suggested that rail guns based on this principle could accelerate payloads into earth orbit or beyond. Find the distance the bar must travel along the rails if it is to reach the escape speed for the earth (11.2 km/s).
For simplicity, assume the net force on the object is equal to the magnetic force, as in parts A and B, even though gravity plays an important role in an actual launch into space.

2. Relevant equations

I know the magnetic force is 588N.
V = at
X = at^2

3. The attempt at a solution

588/25 = 23.52 m/s^2
11200 m/s = 23.52 m/s^2 * t
t = 476.190

x = 23.52 m/s^2 * 476.19^2
5333322.666672 m

Am I missing something, it says that is incorrect....
Phys.Org News Partner Science news on Phys.org
Cougars' diverse diet helped them survive the Pleistocene mass extinction
Cyber risks can cause disruption on scale of 2008 crisis, study says
Mantis shrimp stronger than airplanes
denverdoc is offline
Mar29-07, 10:13 PM
P: 1,351
I think the best approach here might be with the kinematics eqn that relates velocity to distance along which body is uniformly accelerated, since Vi=0 (body at rest): V^2=2a*x
lylos is offline
Mar29-07, 10:16 PM
P: 79
ah, my formulas were wrong... it's x=1/2at^2 and v=at... I should've caught that...

denverdoc is offline
Mar29-07, 10:34 PM
P: 1,351

Rail Guns and acceleration

you miss my point maybe. there is no need to mess with time, but certainly you can get the right answer using that approach. Try it both ways!

Register to reply

Related Discussions
[SOLVED] Acceleration of Guns firing on Moon and Earth Problem--HELP!! Introductory Physics Homework 1
Rail Guns General Physics 8
Rail Gun General Discussion 5
Rail Gun General Engineering 4
Acceleration with a Rail Gun General Physics 0