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When skipping a stone in the water, most people look for flat and light ones. Now, a new study shows that more curved, heavier stones can also produce impressive jumps. And these findings won’t just help you improve your game, they can be applied to the real world, like helping to make airplanes more efficient.
Ryan Palmer is an applied mathematician at the University of Bristol in the UK and co-author of the study. was published this month In the Royal Society.
He and his colleague created a model to study how shape and mass affect the interaction of objects with water. They found that when skipping rocks across a lake, “if you pick something that’s a little bit heavier, you get something called a superelastic response,” Palmer said.
In other words, a heavier object can give an effective breakthrough.
“What happens is the rock hits the water table and because it’s heavier, it sinks further and stays in contact longer,” Palmer said. “That increases the pressure on that rock, which increases the force that lifts it, and you can get a big jump in that response.”
Now, Palmer admitted that while you can get a big jump with heavier stones, it won’t result in as much bounce as with flat stones. Results also depend on the shape of the stone, as too heavy may not work.
“So the take home is really, for a heavier rock that can sink, if it’s a little bit more curved, it might be more likely to float,” he said.
Palmer and his colleague were learning more than just the physics of bouldering. With a mathematical model, they tried to better understand aircraft icing, a phenomenon that occurs when an aircraft flies in very cold weather.
Sometimes puddles of water form on the wing of an airplane, and ice crystals in the air come and either sink into the puddle or float away. If they sink, they cause ice buildup that can be dangerous.
But if they float away, Palmer said, “Well, it’s the same physics and dynamics that you find when you try to pick up a rock and throw it across the lake.”
Knowing where the ice can go is important to better understand whether other parts of the plane need more protection, Palmer said.
He also insisted that commercial aircraft were safe; systems are in place to protect them from dangerous ice buildup. His research aims to improve the effectiveness of those defenses.
“Where we live in a world of climate change and rising fuel costs and things, you’re always trying to be more efficient and so you can design your systems better, protect aircraft better,” he said. “You can cover these weird situations that can happen in an efficient and innovative way.”
While Palmer was looking for practical applications, that wasn’t the only thing he took away from his research.
“Since starting this business, trying and sifting through stones, especially picking out the slightly odd ones, has become even more irresistible,” he said. “Not necessarily so straight.”
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