Motion System Design

# Fun With Fundamentals: Problem 250

Don’t let this problem ruffle your feathers.

### Problem 250: Duck bill

Dale’s Ducks Inc., manufacturer of Lil’ Rubber Duckies, finds his plastic yellow ducklings are in high demand these days. Dale, the founder and owner, needs to buy a new 100-hp motor for his plastics extruder. He burned out the old one, running it flat out 24 hours a day, 364 days a year (only maintenance has to work on Christmas).

A sales representative from a local motor distributor has stopped by to tell him about their new Super-Duper efficiency motor. He claims it will save the Super-Duper motor price difference (\$1,000 higher than the standard motor model) each year in electricity costs alone. After listening to how a proprietary low-temperature coating results in lower operating temperatures, Dale determines that the standard motor efficiency is 93.2% and the Super- Duper motor efficiency is 95.4%. How high must the kilowatt/hour price of electricity be for the salesman’s claim to be true?

### Winners circle

Fun problem 248: TANKS A LOT July, 2001

TOTAL ENTRIES: 58

NUMBER CORRECT: 57 (98%)

WINNER: Blair Zell, Geneva, Ill. BOB’S PRIZE: MechPack-2000 software from UNIK Associates, Milwaukee, Wis., www.engineering-unik.com

Reduce hours spent calculating to minutes. MechPack-2000 helps determine the capacity of flat belts, size pulleys, convert belt speed to rpm, and quickly calculate many other useful factors. Most programs use English and metric units, and on-line help and phone support are available.

### Puzzle us

Get your creative juices flowing and send us your original problems and solutions. If we publish yours, you’ll win a prize. Chuck Krueger, Kings Mountain, N.C., wins MechPack-2000 software for contributing this month’s problem.

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Fun With Fundamentals: Problem 249