Durometer is a technical term and method for measuring the hardness of rubber materials and their imperviousness to lasting indentations, which tells us something about the character.
“You know, it’s when you use a tool or something to do most of the work for you,” she tried explaining. “Have you ever heard of a lever or a fulcrum?”
“Of course.”
“So it is kind of like that. Like when you pry a nail out of wood.” She motioned as if she had a hammer in her hand and pulled back toward her body. “Te longer the handle of the hammer, the more force I can exert on the nail.”
“Tat’s a lever, right?” Mac interrupted, pride overflowing in his voice. “So, it’s kind of like the fly rod,” Mac said, staring at the rod. He grabbed it from the tray and continued. “As I move the rod a short distance with my hand near my shoulder,” he said, moving the rod back and forth like he was casting, “the tip of the rod moves a greater distance.”
He moved the rod back and forth, this time paying attention to the short distance his hand moved and the large distance the rod tip moved.
“Exactly,” Durometer said. “A hammer is also a fulcrum,” she muttered under her breath, not wanting to sound too smart.
“You know what would be better?” Mac responded as if he hadn’t heard her, placing the rod back on the tray. “If you had another pulley attached down here. Wouldn’t that give you some more mechanical advantage?”
It was then that he noticed her pointing to the lump that was partially covered with leaves. Sticking out of that lump was a pulley that had been mounted to the dead log that rested just underneath the tree house. Te end of the rope that she was pulling on was actually going through that pulley as well. Tere was a hook on the end of the rope that acted like a stopper so the rope would not travel all the way out of the pulley and then need to be fed back into it.
“I sometimes use a free pulley when I’m trying to lift something heavy up there,” she said. “You’ll see it on the wall when we climb up. I have all sorts of them for different occasions. I even have one that’s a force multiplier.”
“A what?” Mac responded, turning to look at her with an expres- sion as if he had just smelled a skunk.
“A force multiplier. My dad made it for me,” she said matter-of- factly. “It is a pulley that has a small wheel attached directly to a big wheel. Te small wheel,” she continued, holding her hands out in front of Mac in the shape of a circle the size of an orange,
“has a line of rope coming out of it, kind of like a yo-yo that I can attach to a really heavy object. I can then wind the rope that I will lift with around the larger pulley wheel,” she went on, mov- ing her hands to mimic a circle the size of a basketball. “It is just another example of …”
“Mechanical advantage,” the two of them said together.
She was mostly impressed that this new friend of hers seemed to understand things the same way that she did, even if he needed some help at first. It wasn’t something she ran across with anyone else at school. Once she’d asked one of the girls if she wanted to come over after school. Te girl had said that she wanted to hang out with her friends that were not “nerds.” Te comment seemed like flattery at the time, but now Durometer realized that the girl meant it to be mean. If being smarter than most made her a nerd, that was fine with her. She was fascinated with discovering how things worked and loved solving complex math problems.
Durometer smiled to herself. “Finally,” she thought, “someone who understands.”
MR. JAMES ROBERTSON is a mechanical engineer with Fiat Chrysler Automobiles, and has worked as an engineer in the automotive industry for 21 years. He holds a B.S. in mechanical engineering from Carnegie Mellon University. He has published papers
for SAE and currently works as a corporate-recognized
technical specialist in the chassis suspension systems group. He lives in Michigan with his wife, Elizabeth, and two children, Lorelei and Xavier, all of whom continue to provide inspiration and material for his second book. However, they have not quite learned how to fly fish.
ASC.ARMY.MIL
95
SCIENCE & TECHNOLOGY
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