Question

What makes a paper clip float?

Asked by: Timothy Hicks

Answer

A paper clip will not 'float' on water in the same sense that a cork will. If you position a cork below the surface, it will rise to the surface. A paper clip will not.

If you carefully place the paper clip on the surface of calm water, however, you can keep it from sinking because of surface tension. In a liquid, molecules are attracted by neighboring ones in all directions, except for those at the boundary. The unequal attraction of neighboring molecules at the surface forms a kind of 'skin'. This surface tension is responsible for minimizing the surface area of a free-falling drop of water into a sphere.

If you look closely at an object suspended by surface tension, whether it is a paper clip, insect, leaf, etc. you will notice a slight depression in the surface supporting the object. As long as the pressure exerted by an object is low enough, surface tension can support it. Low pressure requires a large area in contact with the water relative to weight.

Answered by: Paul Walorski, B.A. Physics, Part-time Physics Instructor

Search

Loading






Science Quote

'All of us, are truly and literally a little bit of stardust.'

William Fowler
(1911-1995)
Science Sidebar | Science Education Articles
Cool Summer Science Projects

Why not make science a part of your family’s summer? Perhaps you can set aside one day a week for outdoor projects—maybe Mad Scientist Monday or Scientific Saturday? Here are a few ideas to help get you started. Continue reading ...

10 Ways to Keep Your Kids Interested In Science

Young children are natural scientists: they ask questions, pick up sticks and bugs outside, and are curious about the world around them. But as they get a bit older, many kids gradually lose their interest in science. They might see it as just another task at school, something that doesn't apply to their lives. Of course nothing could be further from the truth, so here are ten ways you can remind your kids that science is everywhere. Most of these are fun for adults, too! Continue reading ...

Top Selling

Here are our physics & astronomy bestsellers:
KonusScience 5 Way Microscope Kit
3D Magnetic Field Tube
Space Wonder Gyroscope
Revolving Multi-Color Fiberoptic Light
Periscope
Deluxe Water Rocket Set
Wood Grain Newtons Cradle
Brush Robot 4M Kit
Solar Radiometer
12 inch Galileo Thermometer

Sponsors

USC University of Southern California Dornsife College Physics and Astronomy Department McMaster University Physics and Astronomy Department