00:01
In this problem on the topic of magnetic forces and the magnetic field, we are told that an electromagnetic rail gun consists of a conducting bar with a mass m and a length l.
00:12
This conducting bar lies on horizontal rails and that is connected to a voltage source.
00:18
Now, this voltage source maintains a constant current in the rails and the bar, and a constant uniform magnetic field flows the region between the rails.
00:28
We want to find the magnitude and the direction of the net force on the conducting bar, as well as the distance the bar must move to attain a speed v, and then use this equation to find the distance that the bar must travel along the rails if it is to reach the escape speed for the earth.
00:53
So we are going to use the equation f is equal to i, lb, sine phi, where f is the force that will be exerted on the bar, i is the current on the rails, and b is the magnetic field.
01:07
The acceleration of the payload, or the bar in this case, a is equal to f over m by newton's second law.
01:15
Now, for part a, we know that phi is equal to 90 degrees, the angle between the magnetic field and the magnetic force.
01:24
So this implies that the force acting on the bar is equal to r...