Add your Article
- Chemistry and Materials
- Revving Up Green Machines
- Cooking Up Superhard Diamonds
- Hitting the redo button on evolution
- Dinosaurs and Fossils
- Tiny Pterodactyl
- Dino Flesh from Fossil Bone
- Ancient Critter Caught Shedding Its Skin
- E Learning Jamaica
- E Learning in Jamaica WIN PRIZES and try our Fun Animated Games
- Results of GSAT are in schools this week
- 2014 GSAT Results for Jamaican Kids
- GSAT Exam Preparation Jamaica
- The Annual GSAT Scholarships
- Tarrant High overcoming the odds
- E Learning in Jamaica WIN PRIZES and try our Fun Animated Games
- GSAT Exams Jamaica Scholarships
- GSAT Practice Papers | GSAT Mathematics | Maths
- Results of GSAT are in schools this week
- GSAT Scholarship
Thinner Air, Less Splatter
Published: 07/05/2010
If you could slow down time, you'd be amazed at the things you could see. In slow motion, for example, you could watch individual drops of rain landing in puddles and making mini-splats. Scientists have been able to observe this process by using cameras that take thousands of pictures every second. Such photos give them the ability to see what our eyes are too slow to catch. Pictures of splashing milk droplets, in particular, have been popular ever since the 1930s, when technology made it possible to capture them. A new experiment adds another twist to these frozen moments in time. Changing the air pressure around a droplet affects the kind of splash it makes. For the study, researchers from the University of Chicago used a sealed chamber that let them change the air pressure inside. At different air pressures, they allowed alcohol drops to fall onto glass slides. They filmed each trial at 47,000 video frames per second. Their results showed that drops hit with smaller splats or no splashing at all when the air pressure was lower than normal. When the scientists increased the air pressure, drops splattered more readily. The researchers also discovered that filling the chamber with lighter gases, such as helium, led to smaller splats compared to ones in the presence of heavier gases. To explain their results, the scientists suggest that, as a drop flattens when it comes in contact with a surface, it spreads out along its edges and pushes against a thin layer of the surrounding gas. The gas resists being trapped, which forces the film's edge upward. This interaction creates the splash. When air pressure is low or the gas is light, the gas can't resist as strongly, and the splat is weaker or never forms in the first place. The scientists were surprised by their discovery. "I don't think anyone ever thought poor little old air could do anything to the splash," says physicist Sidney R. Nagel, who led the Chicago team. Engineers are interested in the work, too. In industry and at home, splashing affects the quality of important processes, including ink-jet printing, engine combustion, and product washing. Finding ways to control the size of a splat could make such jobs a lot more efficient.—E. Sohn
Thinner Air, Less Splatter
