Archives of Ask A Scientist!
About "Ask A Scientist!"
On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.
Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.
Oil floats on water because of two factors: First, teaspoon for teaspoon oil weighs less than water. This makes oil buoyant in water, just like a cork or an air-filled rubber duckie stays on the water's surface in a bathtub or bucket.
Many, but not all, oils are less dense than water. You can demonstrate this by comparing the weight of a beaker of water with a beaker of oil. But that is not the end of the story, for example, most alcohols are also lighter than water, and they do not float.
What is the difference? Oil molecules are hydrophobic (from the Greek meaning fear of water). Most familiar oils do not dissolve in water, instead the molecules cluster toward each other and then float up to the surface. If a large amount of oil is poured into water, the oil will spread out and form a "skin" over the water. Oil laying on the surface of water changes the surface characteristics, such as, how the surface looks to the eye or how it reacts to disturbances like wind. And that's the source of the old saying about calming the sea by "pouring oil on troubled waters."
- Why are combustion reactions exothermic (why is fire hot)? What makes these reactions produce heat the way they do?
- If an object passes in front of a projector/point-source of light that illuminates a screen far away, it will cast a shadow on the screen. Now, if the object moves fast enough, and/or if the screen is far enough, the shadow will move much faster than the object, and at a certain speed of the object, the shadow will move faster than the speed of light. What would a bystander, or a camera, see?
- If solids, like glass and ice, are made of tightly packed molecules, how can we see through them?
- How does sun block work?
- If hydrogen and oxygen are both flammable why doesn't water burn?
- Why do coals appear 'red hot' in a fire and is this the hottest spot in a fire?
- Why is it that when I hold a stick over a fire it ignites without touching the coals?
- Why is vegetable oil able to be used as a power source for automobiles?
- How do you make a man made element?
- How do MRI's work? What are all the ticking and banging noises?