Stopping Sound with Foam. Experiments with this foam (shown under a microscope) showed that at certain frequencies, the bubbles and the surrounding liquid vibrate out of synch in response to an ultrasound wave, completely suppressing the transmission of sound. (Via APS physics).
One of the answers to the topic: Visually stunning math concepts which are easy to explain at Mathematics Stack Exchange.
I think if you look at this animation and think about it long enough, you’ll understand:
- Why circles and right-angle triangles and angles are all related
- Why sine is opposite over hypotenuse and so on
- Why cosine is simply sine but offset by pi/2 radians
MinutePhysics send us a touching message about Venezuelan crisis, it has nothing to do with Science, I know, but is important enough to give it a spot in here. My full support to the people of Venezuela.