Learning Resources

Fun with Fundamentals Puzzler: Shell Shocker

Jan. 1, 2007

Wurme gets to his stand early on opening day, initiating a new era of hunting. He fires up his generator and tunes it to 40 A. If the slug shooter is based on conventional railgun design, how far can he reach with each shot?

Elisabeth Eitel

See the previous problem: Gone to the dogs.

Finagle J. Wurme has missed deer season again. For the tenth straight year, his boss at Charlie's Diner wouldn't give him time off. Randy, the cook, claimed bow season. Andy, the cashier, took gun season, and the new hostess, Sandy, blocked off all the days during muzzle loading for cosmetic surgery.

Machinedesign Com Sites Machinedesign com Files Uploads 2013 05 295 Fundy Rail Gun

Determined to hunt and aided by a loophole in the local county code, Wurme establishes an auxiliary season for electric sporting arms. Using an old rifle stock, some jumper cables, and wire hangers, he concocts a device that would make Horace Smith and Daniel B. Wesson howl.

Wurme gets to his stand early on opening day, initiating a new era of hunting. He fires up his generator and tunes it to 40 A.

If the slug shooter is based on conventional railgun design, how far can he reach with each shot?

Assume the rails are 5 cm apart and that they generate a magnetic field of 5 Tesla.

Assume the horizontal acceleration Ax is assigned a value of 1,000 m/sec² when the projectile is still within the gun. (Once it's left the gun, well ... think about it ...)

Assume the rail is about 1 m long.

Hint: You can the equation X = Xo + Vxo·T + 0.5·Ax·T² to describe the system.

Okay, I've had enough. Give me the solution.

About the Author

Elisabeth Eitel

Elisabeth Eitel was a Senior Editor at Machine Design magazine until 2014. She has a B.S. in Mechanical Engineering from Fenn College at Cleveland State University.