A rail gun uses electromagnetic forces to accelerate a projectile to very high v

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 50.0 g and electrical resistance 0.500 rests on parallel horizontal rails that have negligible electric resistance. The rails are a distance L = 5.00 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 = 0.490 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

s, the coefficient of static friction between the rod and the rails.

Explanation / Answer

The force acting on the rod

F = BIL

= B (V/R) L

When rod moves the applied force is balanced by frictionalforce

==> fs = B(V/R)L

smg= B(V/R)L

==> s = BVL / mgR

= 0.49 * 5 * 0.05 / 0.05*9.8*0.5

= 0.5

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.