Question

A rail gun uses electromagnetic forces to accelerate a projectile to very high velocities. The basic mechanism of acceleration is relatively simple and can be illustrated in the following example. A metal rod of mass 30.0 g and electrical resistance 0.400 ? rests on parallel horizontal rails that have negligible electric resistance. The rails are a distance L = 9.00 cm apart. (Figure 1) The rails are also connected to a voltage source providing a voltage of V = 5.00 V . The rod is placed in a vertical magnetic field. The rod begins to slide when the field reaches the value B = 0.131 T . Assume that the rod has a slightly flattened bottom so that it slides instead of rolling. Use 9.80 m/s2 for the magnitude of the acceleration due to gravity. Find the coefficient of static friction between the rod and the rails.

Answer 1

Answer:

$u_s=0.0802$

Explanation:

To find the coefficient of static friction between the rod and the rails first must find the current

Using law ohm:

$V=I*R$

$I=\frac{V}{R}=5.0v/0.40$

$I=2A$

Now using the Gauss Law of magnetic field solve to us'

$u_s=\frac{I*L*\beta}{m*g}$

Replacing given:

$\beta=0.131T$,$L=9.00cm*\frac{1m}{100cm}=0.09m$, $m=30.0g*\frac{1kg}{1000g}=0.03kg$

$u_s=\frac{2A*0.09m*0.131T}{0.030kg*9.8m/s^2}$

$u_s=0.0802$