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Motion System Design
Fun with Fundamentals: Problem 228

Fun with Fundamentals: Problem 228

Problem 228 - Spittin' mad

Jebediah Dean was settin' in his frictionless wheelchair one sunny afternoon when he decided he needed to git back to the "facilities." Now, ol'Jeb didn't want to set down his 'shine for fear that Blue the Coon-hound would drink it down. As Jeb ponders his predicament, he spits some chaw into a spittoon, causing his chair to move backwards.

Next thing ya know, ol' Jeb's on his way. How many times must he spit to accelerate to 1 m/sec? (Assume ol' Jeb sips on his brew every so often to wet his whistle).

Whatcha need to know:

Jeb (and his frictionless wheelchair) weigh 50 kg

"Projectile" speed = 5 m/sec

Assume the chaw is consistent with water

Solution to July's problem, 227:

You'll be left in the dark if you didn't know the professor's plan won't work, here's why:

As explained by reader, Jun Asai of Chesapeake, Va.,

Since the mass involved = 2 mg of antimatter and 2 mg of matter per day, Einstein's theory of relativity states:

e = mc2

(0.00004kg) × (3 × 108m/sec)2 = 3.6 × 1012 Nm

And we know that there are 86,400 seconds in each day so,

Power = energy divided by time, or:

Considering the efficiency of the professor's machine:

41.67 MW × 0.03 = 12.5 MW

Which is still inadequate, leaving Edisonville in the dark.

Here are the results

The winner is... Fun Problem 226:

Catch of the day, June, 1999:
Total entries: 155
Number correct: 65 (41.9%)
Winner: Lee Ruiz, Indianapolis
Lee's prize: Maple V software
Technical consultant: Jack Couillard, Menasha, Wis.

Related Article

Fun with Fundamentals: Problem 227

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